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1.
PLoS One ; 15(8): e0237883, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32866169

RESUMO

Although whole-genome sequencing has provided novel insights into Neisseria meningitidis, many open reading frames have only been annotated as hypothetical proteins with unknown biological functions. Our previous genetic analyses revealed that the hypothetical protein, NMB1345, plays a crucial role in meningococcal infection in human brain microvascular endothelial cells; however, NMB1345 has no homology to any identified protein in databases and its physiological function could not be elucidated using pre-existing methods. Among the many biological technologies to examine transient protein-protein interaction in vivo, one of the developed methods is genetic code expansion with non-canonical amino acids (ncAAs) utilizing a pyrrolysyl-tRNA synthetase/tRNAPyl pair from Methanosarcina species: However, this method has never been applied to assign function-unknown proteins in pathogenic bacteria. In the present study, we developed a new method to genetically incorporate ncAAs-encoded photocrosslinking probes into N. meningitidis by utilizing a pyrrolysyl-tRNA synthetase/tRNAPyl pair and elucidated the biological function(s) of the NMB1345 protein. The results revealed that the NMB1345 protein directly interacts with PilE, a major component of meningococcal pili, and further physicochemical and genetic analyses showed that the interaction between the NMB1345 protein and PilE was important for both functional pilus formation and meningococcal infectious ability in N. meningitidis. The present study using this new methodology for N. meningitidis provides novel insights into meningococcal pathogenesis by assigning the function of a hypothetical protein.


Assuntos
Aminoácidos/genética , Reagentes para Ligações Cruzadas/metabolismo , Luz , Neisseria meningitidis/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Encéfalo/irrigação sanguínea , Endocitose , Células Endoteliais/microbiologia , Fímbrias Bacterianas/metabolismo , Humanos , Microvasos/patologia , Mutação/genética , Plasmídeos/genética
2.
PLoS One ; 15(8): e0237714, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32804961

RESUMO

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious public health problem. There is limited information regarding the genetics of MRSA strains among the native Iraqi and incoming Syrian refugee communities. We aimed to characterize the genotypes and different virulence factors of MRSA in strains isolated from these two communities. Frozen MRSA strains (125) isolated from the native Iraqi and Syrian refugee communities were used in this study. PCR (singleplex and multiplex) and agr typing was used for the genotypic analysis of different virulence genes. We tested for the presence of virulence genes including pvl, arcA, tst, lukE/lukD, hla, hlb, eta, etb and agr. Prevalence of arcA MRSA in the Iraqi community (56.58%) was significantly higher (p = 0.008) than that in the Syrian refugee community (32.66%). Prevalence of lukE-lukD was also significantly higher (p = 0.001) in the Iraqi (82.89%) compared to that in the Syrian refugee community (57.14%). Further, prevalence of hla MRSA in the Iraqi community was (93.4%) and in the Syrian refugee community was (71.4%); (p = 0.0008). No significant differences were observed in the prevalence of pvl, tst, eta, etb and hlb. The most dominant agr types in both Iraqi (76.1% and 10.5%) and Syrian refugee (44.9% and 18.37%) communities were I and III. To sum up, no significant differences were observed between the groups for a majority of virulence factors. This is the first investigation of MRSA genotypes and virulence in both these communities. These results could be useful for further studies that assess the genetic relatedness of strains in the region for epidemiological and monitoring purposes, which would be crucial to limiting the spread of MRSA.


Assuntos
Resistência a Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Refugiados , Infecções Estafilocócicas/microbiologia , Fatores de Virulência/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Cidades/epidemiologia , Exotoxinas/genética , Exotoxinas/isolamento & purificação , Genes Bacterianos/genética , Técnicas de Genotipagem , Humanos , Iraque/epidemiologia , Meticilina/farmacologia , Meticilina/uso terapêutico , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Testes de Sensibilidade Microbiana , Prevalência , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/epidemiologia , Síria , Transativadores/genética , Transativadores/isolamento & purificação , Fatores de Virulência/isolamento & purificação
3.
Nucleic Acids Res ; 48(14): 7991-8005, 2020 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-32621607

RESUMO

DNA2 is an essential enzyme involved in DNA replication and repair in eukaryotes. In a search for homologues of this protein, we identified and characterised Geobacillus stearothermophilus Bad, a bacterial DNA helicase-nuclease with similarity to human DNA2. We show that Bad contains an Fe-S cluster and identify four cysteine residues that are likely to co-ordinate the cluster by analogy to DNA2. The purified enzyme specifically recognises ss-dsDNA junctions and possesses ssDNA-dependent ATPase, ssDNA binding, ssDNA endonuclease, 5' to 3' ssDNA translocase and 5' to 3' helicase activity. Single molecule analysis reveals that Bad is a processive DNA motor capable of moving along DNA for distances of >4 kb at a rate of ∼200 bp per second at room temperature. Interestingly, as reported for the homologous human and yeast DNA2 proteins, the DNA unwinding activity of Bad is cryptic and can be unmasked by inactivating the intrinsic nuclease activity. Strikingly, our experiments show that the enzyme loops DNA while translocating, which is an emerging feature of processive DNA unwinding enzymes. The bacterial Bad enzymes will provide an excellent model system for understanding the biochemical properties of DNA2-like helicase-nucleases and DNA looping motor proteins in general.


Assuntos
Proteínas de Bactérias/metabolismo , DNA Helicases/metabolismo , DNA de Cadeia Simples/metabolismo , Desoxirribonuclease I/metabolismo , Geobacillus stearothermophilus/enzimologia , Adenosina Trifosfatases/química , Adenosina Trifosfatases/isolamento & purificação , Adenosina Trifosfatases/metabolismo , Trifosfato de Adenosina/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/isolamento & purificação , DNA , DNA Helicases/química , DNA Helicases/isolamento & purificação , Desoxirribonuclease I/química , Desoxirribonuclease I/isolamento & purificação
4.
PLoS One ; 15(7): e0235718, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32639976

RESUMO

Sugar alcohols (polyols) are abundant carbohydrates in lichen-forming algae and transported to other lichen symbionts, fungi, and bacteria. Particularly, ribitol is an abundant polyol in the lichen Cetraria sp. Polyols have important physiological roles in lichen symbiosis, but polyol utilization in lichen-associated bacteria has been largely unreported. Herein, we purified and characterized a novel ribitol dehydrogenase (RDH) from a Cetraria sp.-associated bacterium Sphingomonas sp. PAMC 26621 grown on a minimal medium containing D-ribitol (the RDH hereafter referred to as SpRDH). SpRDH is present as a trimer in its native form, and the molecular weight of SpRDH was estimated to be 39 kDa by SDS-PAGE and 117 kDa by gel filtration chromatography. SpRDH converted D-ribitol to D-ribulose using NAD+ as a cofactor. As far as we know, SpRDH is the first RDH belonging to the medium-chain dehydrogenase/reductase family. Multiple sequence alignments indicated that the catalytic amino acid residues of SpRDH consist of Cys37, His65, Glu66, and Glu157, whereas those of short-chain RDHs consist of Ser, Tyr, and Lys. Furthermore, unlike other short-chain RDHs, SpRDH did not require divalent metal ions for its catalytic activity. Despite SpRDH originating from a psychrophilic Arctic bacterium, Sphingomonas sp., it had maximum activity at 60°C and exhibited high thermal stability within the 4-50°C range. Further studies on the structure/function relationship and catalytic mechanism of SpRDH will expand our understanding of its role in lichen symbiosis.


Assuntos
Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Líquens/microbiologia , Ribitol/metabolismo , Sphingomonas/enzimologia , Desidrogenase do Álcool de Açúcar/isolamento & purificação , Desidrogenase do Álcool de Açúcar/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Homologia de Sequência , Sphingomonas/crescimento & desenvolvimento , Especificidade por Substrato , Desidrogenase do Álcool de Açúcar/genética
5.
Niger J Clin Pract ; 23(7): 912-918, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32620719

RESUMO

Background: Investigating genetic relatedness between methicillin-resistant Staphylococcus aureus (MRSA) strains from humans and different animal species may clarify the epidemiological characteristic of MRSA infections together. Aim: The aim of the study was to perform genotypic characterization and type strains of MRSA isolated from different clinical sources, by molecular techniques. Materials and Methods: The molecular characterization of the strains was performed by polymerase chain reaction (PCR), using several specific oligonucleotides. These were as follows: S. aureus species-specific sau gene, mecA gene coding PBP2a responsible for methicillin resistance, femA gene coding for a protein, which influences the level of methicillin resistance of S. aureus, and is universally present in all MRSA strains; spa gene coding for protein A; coa gene coding for coagulase, and blaZ gene coding for the production of beta-lactamase. To determine the genetic diversity of these strains, random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) was performed. Results: Among the 415 S. aureus strains, 61 were phenotypically identified as MRSA, and confirmed as S. aureus by amplification of sau gene. However, 90.16% of the strains were mecA positive, while all were negative for femA gene. The presence and polymorphism of coa and spa genes were investigated and 83.60% and 18.03% strains were positive for coa and spa, respectively. While these strains were grouped into six coa-types by PCR, no polymorphism was found for spa gene among strains having only single 190 bp of the band. bla genes were found in 75.40% of strains. These strains were divided into 12 RAPD types. Conclusions: The results showed the relatively high heterogeneity and variation of coa gene among MRSA strains, while further studies on sequencing of these strains may identify which sequence type is predominant in this region.


Assuntos
Proteínas de Bactérias/genética , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Reação em Cadeia da Polimerase/métodos , Técnica de Amplificação ao Acaso de DNA Polimórfico/métodos , Animais , Antibacterianos/farmacologia , Proteínas de Bactérias/isolamento & purificação , Coagulase/genética , Genótipo , Humanos , Meticilina , Resistência a Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética
6.
Nat Commun ; 11(1): 3136, 2020 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-32561716

RESUMO

Class 2 CRISPR-Cas proteins have been widely developed as genome editing and transcriptional regulating tools. Class 1 type I CRISPR-Cas constitutes ~60% of all the CRISPR-Cas systems. However, only type I-B and I-E systems have been used to control mammalian gene expression and for genome editing. Here we demonstrate the feasibility of using type I-F system to regulate human gene expression. By fusing transcription activation domain to Pseudomonas aeruginosa type I-F Cas proteins, we activate gene transcription in human cells. In most cases, type I-F system is more efficient than other CRISPR-based systems. Transcription activation is enhanced by elongating the crRNA. In addition, we achieve multiplexed gene activation with a crRNA array. Furthermore, type I-F system activates target genes specifically without off-target transcription activation. These data demonstrate the robustness and programmability of type I-F CRISPR-Cas in human cells.


Assuntos
Proteínas de Bactérias/metabolismo , Proteínas Associadas a CRISPR/metabolismo , Sistemas CRISPR-Cas/genética , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Edição de Genes/métodos , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Proteínas Associadas a CRISPR/genética , Proteínas Associadas a CRISPR/isolamento & purificação , Células HEK293 , Humanos , Pseudomonas aeruginosa/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Ativação Transcricional , Transfecção
7.
PLoS One ; 15(6): e0234958, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32574185

RESUMO

Proteases play an essential role in living organisms and represent one of the largest groups of industrial enzymes. The aim of this work was recombinant production and characterization of a newly identified thermostable protease 1147 from thermophilum indigenous Cohnella sp. A01. Phylogenetic tree analysis showed that protease 1147 is closely related to the cysteine proteases from DJ-1/ThiJ/PfpI superfamily, with the conserved catalytic tetrad. Structural prediction using MODELLER 9v7 indicated that protease 1147 has an overall α/ß sandwich tertiary structure. The gene of protease 1147 was cloned and expressed in Escherichia coli (E. coli) BL21. The recombinant protease 1147 appeared as a homogenous band of 18 kDa in SDS-PAGE, which was verified by western blot and zymography. The recombinant protein was purified with a yield of approximately 88% in a single step using Ni-NTA affinity chromatography. Furthermore, a rapid one-step thermal shock procedure was successfully implemented to purify the protein with a yield of 73%. Using casein as the substrate, Km, and kcat, kcat/Km values of 13.72 mM, 3.143 × 10-3 (s-1), and 0.381 (M-1 S-1) were obtained, respectively. The maximum protease activity was detected at pH = 7 and 60°C with the inactivation rate constant (kin) of 2.10 × 10-3 (m-1), and half-life (t1/2) of 330.07 min. Protease 1147 exhibited excellent stability to organic solvent, metal ions, and 1% SDS. The protease activity was significantly enhanced by Tween 20 and Tween 80 and suppressed by cysteine protease specific inhibitors. Docking results and molecular dynamics (MD) simulation revealed that Tween 20 interacted with protease 1147 via hydrogen bonds and made the structure more stable. CD and fluorescence spectra indicated structural changes taking place at 100°C, very basic and acidic pH, and in the presence of Tween 20. These properties make this newly characterized protease a potential candidate for various biotechnological applications.


Assuntos
Bacillales/enzimologia , Proteínas de Bactérias/química , Peptídeo Hidrolases/química , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/ultraestrutura , Clonagem Molecular , Ensaios Enzimáticos , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Simulação de Dinâmica Molecular , Peso Molecular , Peptídeo Hidrolases/isolamento & purificação , Peptídeo Hidrolases/ultraestrutura , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/ultraestrutura , Especificidade por Substrato
8.
PLoS Genet ; 16(6): e1008837, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32584816

RESUMO

Control of mRNA translation is a crucial regulatory mechanism used by bacteria to respond to their environment. In the soil bacterium Pseudomonas fluorescens, RimK modifies the C-terminus of ribosomal protein RpsF to influence important aspects of rhizosphere colonisation through proteome remodelling. In this study, we show that RimK activity is itself under complex, multifactorial control by the co-transcribed phosphodiesterase trigger enzyme (RimA) and a polyglutamate-specific protease (RimB). Furthermore, biochemical experimentation and mathematical modelling reveal a role for the nucleotide second messenger cyclic-di-GMP in coordinating these activities. Active ribosome regulation by RimK occurs by two main routes: indirectly, through changes in the abundance of the global translational regulator Hfq and directly, with translation of surface attachment factors, amino acid transporters and key secreted molecules linked specifically to RpsF modification. Our findings show that post-translational ribosomal modification functions as a rapid-response mechanism that tunes global gene translation in response to environmental signals.


Assuntos
Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica , Processamento de Proteína Pós-Traducional/genética , Proteínas Ribossômicas/metabolismo , Ribossomos/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Clonagem Molecular , Perfilação da Expressão Gênica , Peptídeo Sintases/genética , Peptídeo Sintases/isolamento & purificação , Peptídeo Sintases/metabolismo , Biossíntese de Proteínas , Proteoma/genética , Proteômica , Pseudomonas fluorescens/genética , RNA Bacteriano/metabolismo , RNA Mensageiro/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Rizosfera , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/isolamento & purificação , Ribossomos/genética
9.
PLoS Genet ; 16(6): e1008897, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32589664

RESUMO

The LonA (or Lon) protease is a central post-translational regulator in diverse bacterial species. In Vibrio cholerae, LonA regulates a broad range of behaviors including cell division, biofilm formation, flagellar motility, c-di-GMP levels, the type VI secretion system (T6SS), virulence gene expression, and host colonization. Despite LonA's role in cellular processes critical for V. cholerae's aquatic and infectious life cycles, relatively few LonA substrates have been identified. LonA protease substrates were therefore identified through comparison of the proteomes of wild-type and ΔlonA strains following translational inhibition. The most significantly enriched LonA-dependent protein was TfoY, a known regulator of motility and the T6SS in V. cholerae. Experiments showed that TfoY was required for LonA-mediated repression of motility and T6SS-dependent killing. In addition, TfoY was stabilized under high c-di-GMP conditions and biochemical analysis determined direct binding of c-di-GMP to LonA results in inhibition of its protease activity. The work presented here adds to the list of LonA substrates, identifies LonA as a c-di-GMP receptor, demonstrates that c-di-GMP regulates LonA activity and TfoY protein stability, and helps elucidate the mechanisms by which LonA controls important V. cholerae behaviors.


Assuntos
Proteínas de Bactérias/antagonistas & inibidores , Cólera/microbiologia , GMP Cíclico/análogos & derivados , Protease La/antagonistas & inibidores , Vibrio cholerae/metabolismo , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Biofilmes/crescimento & desenvolvimento , GMP Cíclico/metabolismo , Modelos Animais de Doenças , Humanos , Camundongos , Mutação , Protease La/genética , Protease La/isolamento & purificação , Protease La/metabolismo , Processamento de Proteína Pós-Traducional , Estabilidade Proteica , Proteólise , Proteômica , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Sistemas de Secreção Tipo VI/genética , Sistemas de Secreção Tipo VI/metabolismo , Vibrio cholerae/genética , Vibrio cholerae/patogenicidade , Virulência/genética
10.
Nat Commun ; 11(1): 2365, 2020 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-32398758

RESUMO

The bacterial effector MavC modulates the host immune response by blocking Ube2N activity employing an E1-independent ubiquitin ligation, catalyzing formation of a γ-glutamyl-ε-Lys (Gln40Ub-Lys92Ube2N) isopeptide crosslink using a transglutaminase mechanism. Here we provide biochemical evidence in support of MavC targeting the activated, thioester-linked Ube2N~ubiquitin conjugate, catalyzing an intramolecular transglutamination reaction, covalently crosslinking the Ube2N and Ub subunits effectively inactivating the E2~Ub conjugate. Ubiquitin exhibits weak binding to MavC alone, but shows an increase in affinity when tethered to Ube2N in a disulfide-linked substrate that mimics the charged E2~Ub conjugate. Crystal structures of MavC in complex with the substrate mimic and crosslinked product provide insights into the reaction mechanism and underlying protein dynamics that favor transamidation over deamidation, while revealing a crucial role for the structurally unique insertion domain in substrate recognition. This work provides a structural basis of ubiquitination by transglutamination and identifies this enzyme's true physiological substrate.


Assuntos
Proteínas de Bactérias/metabolismo , Legionella pneumophila/enzimologia , Transglutaminases/metabolismo , Enzimas de Conjugação de Ubiquitina/metabolismo , Ubiquitina/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/ultraestrutura , Domínio Catalítico/genética , Clonagem Molecular , Cristalografia por Raios X , Modelos Moleculares , Mutagênese Sítio-Dirigida , Ligação Proteica , Estrutura Terciária de Proteína , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/ultraestrutura , Especificidade por Substrato , Transglutaminases/genética , Transglutaminases/isolamento & purificação , Transglutaminases/ultraestrutura , Ubiquitina/isolamento & purificação , Ubiquitina/ultraestrutura , Enzimas de Conjugação de Ubiquitina/isolamento & purificação , Enzimas de Conjugação de Ubiquitina/ultraestrutura , Ubiquitinação
11.
Arch Biochem Biophys ; 688: 108389, 2020 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-32387178

RESUMO

The hydroxymethylpyrimidine phosphate kinases (HMPPK) encoded by the thiD gene are involved in the thiamine biosynthesis pathway, can perform two consecutive phosphorylations of 4-amino-5-hydroxymethyl-2-methyl pyrimidine (HMP) and are found in thermophilic and mesophilic bacteria, but only a few characterizations of mesophilic enzymes are available. The presence of another homolog enzyme (pyridoxal kinase) that can only catalyze the first phosphorylation of HMP and encoded by pdxK gene, has hampered a precise annotation in this enzyme family. Here we report the kinetic characterization of two HMPPK with structure available, the mesophilic and thermophilic enzyme from Salmonella typhimurium (StHMPPK) and Thermus thermophilus (TtHMPPK), respectively. Also, given their high structural similarity, we have analyzed the structural determinants of protein thermal stability in these enzymes by molecular dynamics simulation. The results show that pyridoxal kinases (PLK) from gram-positive bacteria (PLK/HMPPK-like enzymes) constitute a phylogenetically separate group from the canonical PLK, but closely related to the HMPPK, so the PLK/HMPPK-like and canonical PLK, both encoded by pdxK genes, are different and must be annotated distinctly. The kinetic characterization of StHMPPK and TtHMPPK, shows that they perform double phosphorylation on HMP, both enzymes are specific for HMP, not using pyridoxal-like molecules as substrates and their kinetic mechanism involves the formation of a ternary complex. Molecular dynamics simulation shows that StHMPPK and TtHMPPK have striking differences in their conformational flexibility, which can be correlated with the hydrophobic packing and electrostatic interaction network given mainly by salt bridge bonds, but interestingly not by the number of hydrogen bond interactions as reported for other thermophilic enzymes. ENZYMES: EC 2.7.1.49, EC 2.7.4.7, EC 2.7.1.35, EC 2.7.1.50.


Assuntos
Proteínas de Bactérias/química , Fosfotransferases (Aceptor do Grupo Fosfato)/química , Proteínas de Bactérias/isolamento & purificação , Ensaios Enzimáticos , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Cinética , Simulação de Dinâmica Molecular , Fosfotransferases (Aceptor do Grupo Fosfato)/isolamento & purificação , Conformação Proteica , Estabilidade Proteica , Pirimidinas/química , Salmonella typhimurium/enzimologia , Eletricidade Estática , Especificidade por Substrato , Thermus thermophilus/enzimologia
12.
Proc Natl Acad Sci U S A ; 117(11): 6129-6138, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32123104

RESUMO

In oval-shaped Streptococcus pneumoniae, septal and longitudinal peptidoglycan syntheses are performed by independent functional complexes: the divisome and the elongasome. Penicillin-binding proteins (PBPs) were long considered the key peptidoglycan-synthesizing enzymes in these complexes. Among these were the bifunctional class A PBPs, which are both glycosyltransferases and transpeptidases, and monofunctional class B PBPs with only transpeptidase activity. Recently, however, it was established that the monofunctional class B PBPs work together with transmembrane glycosyltransferases (FtsW and RodA) from the shape, elongation, division, and sporulation (SEDS) family to make up the core peptidoglycan-synthesizing machineries within the pneumococcal divisome (FtsW/PBP2x) and elongasome (RodA/PBP2b). The function of class A PBPs is therefore now an open question. Here we utilize the peptidoglycan hydrolase CbpD that targets the septum of S. pneumoniae cells to show that class A PBPs have an autonomous role during pneumococcal cell wall synthesis. Using assays to specifically inhibit the function of PBP2x and FtsW, we demonstrate that CbpD attacks nascent peptidoglycan synthesized by the divisome. Notably, class A PBPs could process this nascent peptidoglycan from a CbpD-sensitive to a CbpD-resistant form. The class A PBP-mediated processing was independent of divisome and elongasome activities. Class A PBPs thus constitute an autonomous functional entity which processes recently formed peptidoglycan synthesized by FtsW/PBP2×. Our results support a model in which mature pneumococcal peptidoglycan is synthesized by three functional entities, the divisome, the elongasome, and bifunctional PBPs. The latter modify existing peptidoglycan but are probably not involved in primary peptidoglycan synthesis.


Assuntos
Amidoidrolases/metabolismo , Proteínas de Bactérias/metabolismo , Parede Celular/metabolismo , Proteínas de Ligação às Penicilinas/metabolismo , Peptidoglicano/metabolismo , Streptococcus pneumoniae/fisiologia , Amidoidrolases/isolamento & purificação , Proteínas de Bactérias/isolamento & purificação , Divisão Celular , Proteínas de Membrana/metabolismo , Uridina Difosfato Ácido N-Acetilmurâmico/análogos & derivados , Uridina Difosfato Ácido N-Acetilmurâmico/metabolismo
13.
Enzyme Microb Technol ; 135: 109489, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32146932

RESUMO

The successful enzymatic synthesis of various ganglioside-related oligosaccharides requires many available glycan-processing enzymes. However, the number of available glycan-processing enzymes remains limited. In this study, the full-length CgtA43456 (ß-(1→4)-N-acetylgalactosaminyltransferase) and CgtB11168 (ß-(1→3)-galactosyltransferase) were successfully produced from Escherichia coli through the optimization of E. coli-preferable codon usage, selection of E. coli strain, and use of the molecular chaperone GroEL-GroES (GroEL/ES). The CgtA43456 enzyme was produced as a soluble form in E. coli C41(DE3) co-expressed with codon-optimized CgtA43456 and GroEL/ES. However, soluble CgtB11168 was well expressed in E. coli C41(DE3) with only the codon-optimized CgtB11168. Rather, when co-expressed with GroEL/ES, total production of CgtB11168 was reduced. Using immobilized-metal affinity chromatography, the CgtA43456 and CgtB11168 proteins were obtained with approximately 75-78 % purity. The purified CgtA43456 showed a specific activity of 21 mU/mg using UDP-N-acetylgalactosamine and GM3 trisaccharide as donor and acceptor, respectively. The purified CgtB11168 catalyzed the transfer of galactose from UDP-Gal to GM2 tetrasaccharide with a specific activity of 16 mU/mg. We propose that they could be used as catalysts for enzymatic synthesis of GM1 ganglioside-related oligosaccharides.


Assuntos
Proteínas de Bactérias/genética , Campylobacter jejuni/enzimologia , Galactosiltransferases/genética , Galactosiltransferases/isolamento & purificação , N-Acetilgalactosaminiltransferases/genética , N-Acetilgalactosaminiltransferases/isolamento & purificação , Proteínas de Bactérias/química , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Campylobacter jejuni/química , Campylobacter jejuni/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Galactosiltransferases/química , Galactosiltransferases/metabolismo , Expressão Gênica , N-Acetilgalactosaminiltransferases/química , N-Acetilgalactosaminiltransferases/metabolismo , Oligossacarídeos/química , Oligossacarídeos/metabolismo , Especificidade por Substrato
14.
Food Chem ; 320: 126599, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32222656

RESUMO

Antifreeze proteins restrict the growth of ice crystals during recrystallization and therefore find application in the protection of food products from damage upon freezing. Hippophae rhamnoides (seabuckthorn) is a freeze tolerant Himalayan shrub exhibiting antifreeze properties. Here, ~39 kDa class IV chitinase (HrCHI4) was purified from seabuckthorn seeds using chitin-affinity chromatography that showed antifreeze property by ice recrystallization inhibition. The application of HrCHI4 in cryopreservation of green beans was analyzed to verify its antifreeze potential. HrCHI4 pretreatment reduced the drip loss and electrolytic leakage in frozen beans, revealing that it preserved the membrane integrity upon cryopreservation. The texture analysis and SEM further validated structural maintenance. The volatile component analysis using GC-MS was performed to evaluate the quality of frozen beans. HrCHI4 contributed positively towards the retention of volatile components after freeze-thaw. In conclusion, a class IV chitinase HrCHI4 was purified from seabuckthorn seeds and its cryoprotective function was reported.


Assuntos
Quitinases/química , Criopreservação/métodos , Conservação de Alimentos/métodos , Verduras , Proteínas Anticongelantes/química , Proteínas Anticongelantes/isolamento & purificação , Proteínas Anticongelantes/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Quitinases/isolamento & purificação , Quitinases/metabolismo , Crioprotetores , Hippophae/enzimologia , Phaseolus
15.
Microbes Environ ; 35(1)2020.
Artigo em Inglês | MEDLINE | ID: mdl-32101840

RESUMO

The genome of Streptomyces scabies, the predominant causal agent of potato common scab, encodes a potential cutinase, the protein Sub1, which was previously shown to be specifically induced in the presence of suberin. The sub1 gene was expressed in Escherichia coli and the recombinant protein Sub1 was purified and characterized. The enzyme was shown to be versatile because it hydrolyzes a number of natural and synthetic substrates. Sub1 hydrolyzed p-nitrophenyl esters, with the hydrolysis of those harboring short carbon chains being the most effective. The Vmax and Km values of Sub1 for p-nitrophenyl butyrate were 2.36 mol g-1 min-1 and 5.7 10-4 M, respectively. Sub1 hydrolyzed the recalcitrant polymers cutin and suberin because the release of fatty acids from these substrates was observed following the incubation of the enzyme with these polymers. Furthermore, the hydrolyzing activity of the esterase Sub1 on the synthetic polymer polyethylene terephthalate (PET) was demonstrated by the release of terephthalic acid (TA). Sub1 activity on PET was markedly enhanced by the addition of Triton and was shown to be stable at 37°C for at least 20 d.


Assuntos
Proteínas de Bactérias/metabolismo , Hidrolases de Éster Carboxílico/metabolismo , Doenças das Plantas/microbiologia , Polímeros/metabolismo , Streptomyces/enzimologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Hidrolases de Éster Carboxílico/genética , Hidrolases de Éster Carboxílico/isolamento & purificação , Ácidos Graxos/metabolismo , Hidrólise , Ácidos Ftálicos/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Solanum tuberosum/microbiologia , Streptomyces/genética
16.
Biochemistry ; 59(8): 983-991, 2020 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-32045213

RESUMO

The second messenger bis(3',5')-cyclic dimeric guanosine monophosphate (c-di-GMP) regulates numerous important physiological functions in bacteria. In this study, we identified and characterized the first dimeric, full-length, non-heme iron-bound phosphodiesterase (PDE) containing bacterial hemerythrin and HD-GYP domains (Bhr-HD-GYP). We found that the amino acid sequence encoded by the FV185_09380 gene from Ferrovum sp. PN-J185 contains an N-terminal bacterial hemerythrin domain and a C-terminal HD-GYP domain, which is characteristic of proteins with PDE activity toward c-di-GMP. Inductively coupled plasma optical emission spectroscopy analyses showed that Bhr-HD-GYP contains 4 equiv of iron atoms per subunit, suggesting both hemerythrin and HD-GYP domains have non-heme di-iron sites. A redox-dependent spectral change expected for oxo-bridged non-heme iron with carboxylate ligands was observed, and this redox interconversion was reversible. However, unlike marine invertebrate hemerythrin, which functions as an oxygen-binding protein, Bhr-HD-GYP did not form an oxygen adduct because of rapid autoxidation. The reduced ferrous iron complex of the protein catalyzed the hydrolysis of c-di-GMP to its linearized product, 5'-phosphoguanylyl-(3',5')-guanosine (pGpG), whereas the oxidized ferric iron complex had no significant activity. These results suggest that Bhr-HD-GYP is a redox and oxygen sensor enzyme that regulates c-di-GMP levels in response to changes in cellular redox status or oxygen concentration. Our study may lead to an improved understanding of the physiology of iron-oxidizing bacterium Ferrovum sp. PN-J185.


Assuntos
Proteínas de Bactérias/química , Hemeritrina/química , Diester Fosfórico Hidrolases/química , Sequência de Aminoácidos , Proteínas de Bactérias/isolamento & purificação , Betaproteobacteria/enzimologia , Catálise , GMP Cíclico/análogos & derivados , GMP Cíclico/química , Ensaios Enzimáticos , Hemeritrina/isolamento & purificação , Hidrólise , Ferro/química , Oxirredução , Diester Fosfórico Hidrolases/isolamento & purificação , Domínios Proteicos , Alinhamento de Sequência
17.
Appl Microbiol Biotechnol ; 104(5): 2067-2077, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31932896

RESUMO

Halohydrin dehalogenases (HHDHs) have attracted much attention due to their ability to synthesize enantiomerically enriched epoxides and ß-haloalcohols. However, most of the HHDHs exhibit low enantioselectivity. Here, a HHDH from the alphaproteobacteria isolate 46_93_T64 (AbHHDH), which shows only poor enantioselectivity in the catalytic resolution of rac-PGE (E = 9.9), has been subjected to protein engineering to enhance its enantioselectivity. Eight mutants (R89K, R89Y, V137I, P178A, N179Q, N179L, F187L, F187A) showed better enantioselectivity than the wild type. The best single mutant N179L (E = 93.0) showed a remarkable 9.4-fold increase in the enantioselectivity. Then, the single mutations were combined to produce the double, triple, quadruple, and quintuple mutants. Among the combinational mutants, the best variant (R89Y/N179L) showed an increased E value of up to 48. The E values of the variants N179L and R89Y/N179L for other epoxides 2-7 were 12.2 to > 200, which showed great improvement compared to 1.2 to 10.5 for the wild type. Using the variant N179L, enantiopure (R)-PGE with > 99% ee could be readily prepared, affording a high yield and a high concentration.


Assuntos
Proteínas de Bactérias/metabolismo , Compostos de Epóxi/química , Compostos de Epóxi/metabolismo , Hidrolases/metabolismo , Alphaproteobacteria/enzimologia , Alphaproteobacteria/genética , Alphaproteobacteria/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Biocatálise , Hidrolases/química , Hidrolases/genética , Hidrolases/isolamento & purificação , Cinética , Modelos Moleculares , Mutação , Engenharia de Proteínas , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Estereoisomerismo , Especificidade por Substrato
18.
Appl Microbiol Biotechnol ; 104(5): 2079-2096, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31980921

RESUMO

PcMulGH9, a novel glycoside hydrolase family 9 (GH9) from Paenibacillus curdlanolyticus B-6, was successfully expressed in Escherichia coli. It is composed of a catalytic domain of GH9, two domains of carbohydrate-binding module family 3 (CBM3) and two domains of fibronectin type 3 (Fn3). The PcMulGH9 enzyme showed broad activity towards the ß-1,4 glycosidic linkages of cellulose, mannan and xylan, including cellulose and xylan contained in lignocellulosic biomass, which is rarely found in GH9. The enzyme hydrolysed substrates with bifunctional endo-/exotypes cellulase, mannanase and xylanase activities, but predominantly exhibited exo-activities. This enzyme released cellobiose as a major product from cellohexaose, while mannotriose and xylotriose were major hydrolysis products from mannohexaose and xylohexaose, respectively. Moreover, PcMulGH9 could hydrolyse untreated corn hull and rice straw into xylo- and cello-oligosaccharides. Enzyme kinetics, site-directed mutagenesis and molecular docking revealed that Met394, located at the binding subsite + 2, was involved in broad substrate specificity of PcMulGH9 enzyme. This study offers new knowledge of the multifunctional cellulase/mannanase/xylanase in GH9. The PcMulGH9 enzyme showed a novel function of GH9, which increases its potential for saccharification of lignocellulosic biomass into value-added products, especially oligosaccharides.


Assuntos
Proteínas de Bactérias/metabolismo , Glicosídeo Hidrolases/metabolismo , Enzimas Multifuncionais/metabolismo , Paenibacillus/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Domínio Catalítico , Celulase/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Glicosídeo Hidrolases/química , Glicosídeo Hidrolases/genética , Glicosídeo Hidrolases/isolamento & purificação , Hidrólise , Cinética , Manosidases/metabolismo , Simulação de Acoplamento Molecular , Enzimas Multifuncionais/química , Enzimas Multifuncionais/genética , Enzimas Multifuncionais/isolamento & purificação , Mutação , Oligossacarídeos/biossíntese , Paenibacillus/genética , Paenibacillus/metabolismo , Polissacarídeos/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Especificidade por Substrato , Xilosidases/metabolismo
19.
Int J Mol Sci ; 21(1)2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31906428

RESUMO

Although prevalent in the determination of protein structures; crystallography always has the bottleneck of obtaining high-quality protein crystals for characterizing a wide range of proteins; especially large protein complexes. Stable fragments or domains of proteins are more readily to crystallize; which prompts the use of in situ proteolysis to remove flexible or unstable structures for improving crystallization and crystal quality. In this work; we investigated the effects of in situ proteolysis by chymotrypsin on the crystallization of the XcpVWX complex from the Type II secretion system of Pseudomonas aeruginosa. Different proteolysis conditions were found to result in two distinct lattices in the same crystallization solution. With a shorter chymotrypsin digestion at a lower concentration; the crystals exhibited a P3 hexagonal lattice that accommodates three complex molecules in one asymmetric unit. By contrast; a longer digestion with chymotrypsin of a 10-fold higher concentration facilitated the formation of a compact P212121 orthorhombic lattice with only one complex molecule in each asymmetric unit. The molecules in the hexagonal lattice have shown high atomic displacement parameter values compared with the ones in the orthorhombic lattice. Taken together; our results clearly demonstrate that different proteolysis conditions can result in the generation of distinct lattices in the same crystallization solution; which can be exploited in order to obtain different crystal forms of a better quality.


Assuntos
Quimotripsina , Cristalização/métodos , Complexos Multiproteicos/química , Proteínas de Bactérias/química , Proteínas de Bactérias/isolamento & purificação , Cristalografia por Raios X , Proteínas de Membrana/química , Proteínas de Membrana/isolamento & purificação , Complexos Multiproteicos/isolamento & purificação , Conformação Proteica , Proteólise , Sistemas de Secreção Tipo II/química
20.
Nat Commun ; 11(1): 564, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31992701

RESUMO

Detergents enable the purification of membrane proteins and are indispensable reagents in structural biology. Even though a large variety of detergents have been developed in the last century, the challenge remains to identify guidelines that allow fine-tuning of detergents for individual applications in membrane protein research. Addressing this challenge, here we introduce the family of oligoglycerol detergents (OGDs). Native mass spectrometry (MS) reveals that the modular OGD architecture offers the ability to control protein purification and to preserve interactions with native membrane lipids during purification. In addition to a broad range of bacterial membrane proteins, OGDs also enable the purification and analysis of a functional G-protein coupled receptor (GPCR). Moreover, given the modular design of these detergents, we anticipate fine-tuning of their properties for specific applications in structural biology. Seen from a broader perspective, this represents a significant advance for the investigation of membrane proteins and their interactions with lipids.


Assuntos
Proteínas da Membrana Bacteriana Externa/química , Proteínas da Membrana Bacteriana Externa/isolamento & purificação , Detergentes/química , Receptores Acoplados a Proteínas-G/química , Receptores Acoplados a Proteínas-G/isolamento & purificação , Proteínas de Bactérias/química , Proteínas de Bactérias/isolamento & purificação , Escherichia coli , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/isolamento & purificação , Espectrometria de Massas , Lipídeos de Membrana , Modelos Moleculares , Peptídeo Hidrolases/química , Peptídeo Hidrolases/isolamento & purificação , Redobramento de Proteína , Solubilidade
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