Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 62
Filtrar
1.
Genes Dev ; 35(3-4): 286-299, 2021 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-33446571

RESUMO

RNase E is an essential, multifunctional ribonuclease encoded in E. coli by the rne gene. Structural analysis indicates that the ribonucleolytic activity of this enzyme is conferred by rne-encoded polypeptide chains that (1) dimerize to form a catalytic site at the protein-protein interface, and (2) multimerize further to generate a tetrameric quaternary structure consisting of two dimerized Rne-peptide chains. We identify here a mutation in the Rne protein's catalytic region (E429G), as well as a bacterial cell wall peptidoglycan hydrolase (Amidase C [AmiC]), that selectively affect the specific activity of the RNase E enzyme on long RNA substrates, but not on short synthetic oligonucleotides, by enhancing enzyme multimerization. Unlike the increase in specific activity that accompanies concentration-induced multimerization, enhanced multimerization associated with either the E429G mutation or interaction of the Rne protein with AmiC is independent of the substrate's 5' terminus phosphorylation state. Our findings reveal a previously unsuspected substrate length-dependent regulatory role for RNase E quaternary structure and identify cis-acting and trans-acting factors that mediate such regulation.


Assuntos
Endorribonucleases/química , Endorribonucleases/metabolismo , Proteínas de Escherichia coli/química , Escherichia coli/enzimologia , Escherichia coli/genética , Modelos Moleculares , Amidoidrolases/metabolismo , Domínio Catalítico , Endorribonucleases/genética , Proteínas de Escherichia coli/genética , Mutação/genética , Estrutura Quaternária de Proteína , RNA Bacteriano/metabolismo , Regulação para Cima/genética
2.
J Biol Chem ; 298(9): 102256, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35839855

RESUMO

Nuclear lamins maintain the nuclear envelope structure by forming long linear filaments via two alternating molecular arrangements of coiled-coil dimers, known as A11 and A22 binding modes. The A11 binding mode is characterized by the antiparallel interactions between coil 1b domains, whereas the A22 binding mode is facilitated by interactions between the coil 2 domains of lamin. The junction between A11- and A22-interacting dimers in the lamin tetramer produces another parallel head-tail interaction between coil 1a and the C-terminal region of coil 2, called the ACN interaction. During mitosis, phosphorylation in the lamin N-terminal head region by the cyclin-dependent kinase (CDK) complex triggers depolymerization of lamin filaments, but the associated mechanisms remain unknown at the molecular level. In this study, we revealed using the purified proteins that phosphorylation by the CDK1 complex promotes disassembly of lamin filaments by directly abolishing the ACN interaction between coil 1a and the C-terminal portion of coil 2. We further observed that this interaction was disrupted as a result of alteration of the ionic interactions between coil 1a and coil 2. Combined with molecular modeling, we propose a mechanism for CDK1-dependent disassembly of the lamin filaments. Our results will help to elucidate the cell cycle-dependent regulation of nuclear morphology at the molecular level.


Assuntos
Proteína Quinase CDC2 , Filamentos Intermediários , Lamina Tipo A , Proteína Quinase CDC2/química , Humanos , Filamentos Intermediários/química , Lamina Tipo A/química , Polimerização , Domínios Proteicos
3.
PLoS Pathog ; 17(2): e1009263, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33524062

RESUMO

Bacteria utilize endoribonuclease-mediated RNA processing and decay to rapidly adapt to environmental changes. Here, we report that the modulation of hns mRNA stability by the endoribonuclease RNase G plays a key role in Salmonella Typhimurium pathogenicity. We found that RNase G determines the half-life of hns mRNA by cleaving its 5' untranslated region and that altering its cleavage sites by genome editing stabilizes hns mRNA, thus decreasing S. Typhimurium virulence in mice. Under anaerobic conditions, the FNR-mediated transcriptional repression of rnc encoding RNase III, which degrades rng mRNA, and simultaneous induction of rng transcription resulted in rapid hns mRNA degradation, leading to the derepression of genes involved in the Salmonella pathogenicity island 1 (SPI-1) type III secretion system (T3SS). Together, our findings show that RNase III and RNase G levels-mediated control of hns mRNA abundance acts as a regulatory pathway upstream of a complex feed-forward loop for SPI-1 expression.


Assuntos
Regulação Bacteriana da Expressão Gênica , Ilhas Genômicas , Estabilidade de RNA , RNA Bacteriano/metabolismo , Salmonella typhimurium/patogenicidade , Animais , Proteínas de Bactérias/genética , Sítios de Ligação , Proteínas de Ligação a DNA/genética , Feminino , Camundongos , Camundongos Endogâmicos BALB C , Oxigênio/metabolismo , Salmonella typhimurium/genética , Transcriptoma , Sistemas de Secreção Tipo III/genética , Sistemas de Secreção Tipo III/metabolismo , Virulência/genética
4.
BMC Genomics ; 19(1): 535, 2018 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-30005607

RESUMO

BACKGROUND: The Zika virus (ZIKV) can cause microcephaly and congenital abnormalities in the foetus. Recent studies have provided insights into the evolution of ZIKV from the current and previous outbreaks, but the types have not been determined. RESULTS: We analysed the insertions and deletions (InDels) in 212 ZIKV polyproteins and 5 Dengue virus (DENV) reference sequences. Spearman correlation tests for the minimum InDel (minInDel) patterns were used to assess the type of polyprotein. Using the minInDel frequencies calculated from polyproteins with 11 elements, likelihood estimation was conducted to correct the evolutionary distance. The minInDel-corrected tree topology clearly distinguished between the ZIKV types (I and II) with a unique minInDel character in the E protein. From the 10-year average genetic distance, the African and Asian lineages of ZIKV-II were estimated to have occurred ~ 270 years ago, which is unlikely for ZIKV-I. CONCLUSIONS: The minInDel pattern analysis showed that the minInDel in the E protein is targetable for the rapid detection and determination of the virus types.


Assuntos
Genoma Viral , Zika virus/genética , Sequência de Aminoácidos , Dengue/patologia , Dengue/virologia , Vírus da Dengue/genética , Vírus da Dengue/isolamento & purificação , Evolução Molecular , Frequência do Gene , Humanos , Mutação INDEL , Poliproteínas/genética , Alinhamento de Sequência , Proteínas Virais/genética , Zika virus/isolamento & purificação , Infecção por Zika virus/patologia , Infecção por Zika virus/virologia
5.
Curr Microbiol ; 72(6): 716-22, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26888524

RESUMO

RNase E plays an important role in the degradation and processing of RNA in Escherichia coli. The enzymatic activity of RNase E is controlled by the protein inhibitors RraA and RraB. The marine pathogenic bacterium Vibrio vulnificus also contains homologs of RNase E and RraA, designated as RNase EV, RraAV1, and RraAV2. Here, we report that RraAV1 actively inhibits the enzymatic activity of RNase EV in vivo and in vitro by interacting with the C-terminal domain of RNase EV. Coexpression of RraAV1 reduced ribonucleolytic activity in the cells overproducing RNase EV and consequently restored normal growth of these cells. An in vitro cleavage assay further demonstrated that RraAV1 efficiently inhibits the ribonucleolytic activity of RNase EV on BR10 + hpT, a synthetic oligonucleotide containing the RNase E cleavage site of RNA I. Our findings suggest that RraAV1 plays an active role in RNase EV-mediated RNA cleavage in V. vulnificus.


Assuntos
Proteínas de Bactérias/metabolismo , Endorribonucleases/metabolismo , Escherichia coli/genética , Vibrio vulnificus/enzimologia , Proteínas de Bactérias/genética , Endorribonucleases/genética , Escherichia coli/enzimologia , Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Regulação Bacteriana da Expressão Gênica , RNA Bacteriano/genética , RNA Bacteriano/metabolismo , Vibrio vulnificus/genética
6.
Nucleic Acids Res ; 42(7): 4669-81, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24489121

RESUMO

Here, we report a resistance mechanism that is induced through the modulation of 16S ribosomal RNA (rRNA) processing on the exposure of Escherichia coli cells to aminoglycoside antibiotics. We observed decreased expression levels of RNase G associated with increased RNase III activity on rng mRNA in a subgroup of E. coli isolates that transiently acquired resistance to low levels of kanamycin or streptomycin. Analyses of 16S rRNA from the aminoglycoside-resistant E. coli cells, in addition to mutagenesis studies, demonstrated that the accumulation of 16S rRNA precursors containing 3-8 extra nucleotides at the 5' terminus, which results from incomplete processing by RNase G, is responsible for the observed aminoglycoside resistance. Chemical protection, mass spectrometry analysis and cell-free translation assays revealed that the ribosomes from rng-deleted E. coli have decreased binding capacity for, and diminished sensitivity to, streptomycin and neomycin, compared with wild-type cells. It was observed that the deletion of rng had similar effects in Salmonella enterica serovar Typhimurium strain SL1344. Our findings suggest that modulation of the endoribonucleolytic activity of RNase III and RNase G constitutes a previously uncharacterized regulatory pathway for adaptive resistance in E. coli and related gram-negative bacteria to aminoglycoside antibiotics.


Assuntos
Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Endorribonucleases/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/efeitos dos fármacos , Inibidores da Síntese de Proteínas/farmacologia , RNA Ribossômico 16S/metabolismo , Ribonuclease III/metabolismo , Aminoglicosídeos/metabolismo , Antibacterianos/metabolismo , Farmacorresistência Bacteriana , Endorribonucleases/genética , Escherichia coli/enzimologia , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Proteínas de Escherichia coli/genética , Biossíntese de Proteínas/efeitos dos fármacos , Inibidores da Síntese de Proteínas/metabolismo , Precursores de RNA/química , Precursores de RNA/metabolismo , Processamento Pós-Transcricional do RNA , RNA Ribossômico 16S/química , Subunidades Ribossômicas Menores de Bactérias/metabolismo , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/genética
7.
J Proteome Res ; 14(6): 2446-56, 2015 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-25871347

RESUMO

Granulosa cell tumor (GCT) is a rare form of ovarian cancer classified as a sex cord-stromal tumor. The c.402C→G missense mutation in the FOXL2 gene that changes cysteine 134 to tryptophan (C134W) is found in more than 97% of adult-type GCTs, and the C134W FOXL2 mutant is hyperphosphorylated. We identified three differential phosphorylation sites, at serine 33 (S33), tyrosine 186 (Y186), and serine 238 (S238), of the C134W mutant by tandem mass spectrometry. Among these sites, antibodies were raised against the pS33 and pY186 epitopes using specific peptides, and they were tested by immunostaining tissue microarrays of archival adult-type GCT specimens, other tumors, and normal tissues. The pS33 antibody showed greater sensitivity and specificity for the detection of adult-type GCTs than that of the other phospho and nonphospho antibodies. The specificity of the pS33 antibody to the pS33 epitope was further confirmed by enriching the pS33 peptide by affinity chromatography using the immobilized antibody, followed by mass spectrometric and western blot analyses from whole cell lysates of the adult-type GCT cell line, KGN. pS33 FOXL2 immunostaining levels were significantly higher in adult-type GCTs than those in other tumors and tissues. The receiver operating characteristic curve analysis of pS33 FOXL2 showed high sensitivity (1.0) and specificity (0.76) to adult-type GCTs with a cutoff score of >30% positive cells, and the area under the curve was 0.96. This suggests the potential of pS33 FOXL2 to serve as a new biomarker for the diagnosis of adult-type GCT.


Assuntos
Biomarcadores/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Tumor de Células da Granulosa/metabolismo , Proteínas Nucleares/metabolismo , Adulto , Anticorpos/imunologia , Células Cultivadas , Cromatografia de Afinidade , Proteína Forkhead Box L2 , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/imunologia , Humanos , Masculino , Mutação , Proteínas Nucleares/genética , Proteínas Nucleares/imunologia , Fosforilação
8.
Infect Immun ; 83(11): 4266-76, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26283336

RESUMO

MdsABC is a Salmonella-specific tripartite efflux pump that has been implicated in the virulence of Salmonella enterica serovar Typhimurium; however, little is known about the virulence factors associated with this pump. We observed MdsABC expression-dependent alterations in the degree of resistance to extracellular oxidative stress and macrophage-mediated killing. Thin-layer chromatography and tandem mass spectrometry analyses revealed that overexpression of MdsABC led to increased secretion of 1-palmitoyl-2-stearoyl-phosphatidylserine (PSPS), affecting the ability of the bacteria to invade and survive in host cells. Overexpression of MdsABC and external addition of PSPS similarly rendered the mdsABC deletion strain resistant to diamide. Diagonal gel analysis showed that PSPS treatment reduced the diamide-mediated formation of disulfide bonds, particularly in the membrane fraction of the bacteria. Salmonella infection of macrophages induced the upregulation of MdsABC expression and led to an increase of intracellular bacterial number and host cell death, similar to the effects of MdsABC overexpression and PSPS pretreatment on the mdsABC deletion strain. Our study shows that MdsABC mediates a previously uncharacterized pathway that involves PSPS as a key factor for the survival and virulence of S. Typhimurium in phagocytic cells.


Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Infecções por Salmonella/microbiologia , Salmonella typhimurium/metabolismo , Salmonella typhimurium/patogenicidade , Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica , Humanos , Macrófagos/metabolismo , Macrófagos/microbiologia , Proteínas de Membrana Transportadoras/genética , Salmonella typhimurium/genética , Virulência
9.
Appl Environ Microbiol ; 81(15): 5266-77, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26025888

RESUMO

The bacterial 2-nitroreductase NbaA is the primary enzyme initiating the degradation of 2-nitrobenzoate (2-NBA), and its activity is controlled by posttranslational modifications. To date, the structure of NbaA remains to be elucidated. In this study, the crystal structure of a Cys194Ala NbaA mutant was determined to a 1.7-Å resolution. The substrate analog 2-NBA methyl ester was used to decipher the substrate binding site by inhibition of the wild-type NbaA protein. Tandem mass spectrometry showed that 2-NBA methyl ester produced a 2-NBA ester bond at the Tyr193 residue in the wild-type NbaA but not residues in the Tyr193Phe mutant. Moreover, covalent binding of the 2-NBA methyl ester to Tyr193 reduced the reactivity of the Cys194 residue on the peptide link. The Tyr193 hydroxyl group was shown to be essential for enzyme catalysis, as a Tyr193Phe mutant resulted in fast dissociation of flavin mononucleotide (FMN) from the protein with the reduced reactivity of Cys194. FMN binding to NbaA varied with solution NaCl concentration, which was related to the catalytic activity but not to cysteine reactivity. These observations suggest that the Cys194 reactivity is negatively affected by a posttranslational modification of the adjacent Tyr193 residue, which interacts with FMN and the substrate in the NbaA catalytic site.


Assuntos
Nitrobenzoatos/química , Nitrobenzoatos/metabolismo , Nitrorredutases/química , Nitrorredutases/metabolismo , Pseudomonas fluorescens/enzimologia , Sítios de Ligação , Cristalografia por Raios X , Modelos Moleculares , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Mutação de Sentido Incorreto , Ligação Proteica , Conformação Proteica , Processamento de Proteína Pós-Traducional , Cloreto de Sódio/metabolismo , Espectrometria de Massas em Tandem
10.
Acta Crystallogr D Biol Crystallogr ; 70(Pt 10): 2619-30, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25286846

RESUMO

The Gram-positive bacteria Mycobacterium tuberculosis and M. bovis are causative agents of tuberculosis in humans and cattle. The lipoprotein LprF is found in M. tuberculosis and M. bovis but not in the nonpathogenic M. smegmatis. To date, the role of LprF remains to be elucidated. In this study, the crystal structure of LprF has been determined at 1.1 Šresolution. The overall structure is similar to that of a homologue, LprG, with a central hydrophobic cavity that binds a triacylated glycolipid. LprF exhibited a central cavity structure similar to that of LprG, but with a smaller cavity that binds two alkyl chains. Consistently, subsequent mass-spectrometric analysis revealed that the bound ligand was a diacylated glycolipid, as found in the structure. Furthermore, an increased ratio of lipoarabinomannan to lipomannan in the mycobacterial cell wall was observed when lprF was introduced into M. smegmatis. These observations suggested that LprF transfers the diacylated glycolipid from the plasma membrane to the cell wall, which might be related to the pathogenesis of the bacteria.


Assuntos
Proteínas de Bactérias/química , Lipoproteínas/química , Mycobacterium bovis/química , Mycobacterium tuberculosis/química , Antituberculosos/farmacologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Parede Celular/metabolismo , Cristalografia por Raios X , Farmacorresistência Bacteriana/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Etambutol/farmacologia , Glicolipídeos/metabolismo , Lipopolissacarídeos/metabolismo , Lipoproteínas/genética , Lipoproteínas/metabolismo , Modelos Moleculares , Mycobacterium bovis/metabolismo , Mycobacterium bovis/patogenicidade , Mycobacterium smegmatis/efeitos dos fármacos , Mycobacterium smegmatis/genética , Mycobacterium smegmatis/metabolismo , Mycobacterium tuberculosis/metabolismo , Mycobacterium tuberculosis/patogenicidade , Conformação Proteica , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
11.
Biochem Biophys Res Commun ; 446(4): 971-6, 2014 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-24657263

RESUMO

Salmonella enterica serovar Typhimurium (S. Typhimurium) is a facultative intracellular pathogen with the ability to survive and replicate in macrophages. Periplasmic copper binding protein CueP is known to confer copper resistance to S. Typhimurium, and has been implicated in ROS scavenge activity by transferring the copper ion to a periplasmic superoxide dismutase or by directly reducing the copper ion. Structural and biochemical studies on CueP showed that its copper binding site is surrounded by conserved cysteine residues. Here, we present evidence that periplasmic disulfide isomerase DsbC plays a key role in maintaining CueP protein in the reduced state. We observed purified DsbC protein efficiently reduced the oxidized form of CueP, and that it acted on two (Cys104 and Cys172) of the three conserved cysteine residues. Furthermore, we found that a surface-exposed conserved phenylalanine residue in CueP was important for this process, which suggests that DsbC specifically recognizes the residue of CueP. An experiment using an Escherichia coli system confirmed the critical role played by DsbC in the ROS scavenge activity of CueP. Taken together, we propose a molecular insight into how CueP collaborates with the periplasmic disulfide reduction system in the pathogenesis of the bacteria.


Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Transporte/metabolismo , Isomerases de Dissulfetos de Proteínas/metabolismo , Infecções por Salmonella/microbiologia , Salmonella typhimurium/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Transporte/química , Cobre/metabolismo , Peróxido de Hidrogênio/metabolismo , Ferro/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Isomerases de Dissulfetos de Proteínas/química , Espécies Reativas de Oxigênio/metabolismo , Salmonella typhimurium/química , Alinhamento de Sequência
12.
Sci Rep ; 14(1): 15542, 2024 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-38969698

RESUMO

There are numerous species in the Erwiniaceae family that are important for agricultural and clinical purposes. Here we described the Erwiniaceae bacterium PD-1 isolated from mushroom (Pleurotus eryngii) compost. Comparative genomic and phylogenetic analyses showed that the strain PD-1 was assigned to a new genus and species, Paramixta manurensis gen. nov., sp. nov. in the family Erwiniaceae. From the average amino acid index, we identified the five AroBEKAC proteins in the shikimate pathway as a minimal set of molecular markers to reconstruct the phylogenetic tree of the Erwiniaceae species. The strain PD-1 containing annotated genes for ubiquinone and menaquinone produced a higher level of ubiquinone (Q8) than demethylmenaquinone (DMK8) and menaquinone (MK8) in anaerobic condition compared to aerobic condition, as similarly did the reference strains from the genera Mixta and Erwinia. Results from fatty acid methyl ester and numerical analyses of strain PD-1 showed a similarity to species of the genera Mixta and Winslowiella. This study revealed that the strain's ability to utilize polyols, such as glycerol, erythritol, and D-arabitol, distinguished the strain PD-1 from the nearest relative and other type strains. The analyzed genetic markers and biochemical properties of the strain PD-1 suggest its potential role in the process of mushroom compost through the degradation of carbohydrates and polysaccharides derived from fungi and plants. Additionally, it can produce a high concentration of indole-3-acetic acid as a plant growth-promoting agent.


Assuntos
Agaricales , Ácidos Indolacéticos , Filogenia , Agaricales/genética , Agaricales/metabolismo , Agaricales/classificação , Ácidos Indolacéticos/metabolismo , Compostagem , Microbiologia do Solo , RNA Ribossômico 16S/genética
13.
J Bacteriol ; 195(2): 180-92, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23123905

RESUMO

2-Nitrobenzoate 2-nitroreductase (NbaA) of Pseudomonas fluorescens strain KU-7 is a unique enzyme, transforming 2-nitrobenzoic acid (2-NBA) and 2,4-dinitrobenzoic acid (2,4-DNBA) to the 2-hydroxylamine compounds. Sequence comparison reveals that NbaA contains a conserved cysteine residue at position 141 and two variable regions at amino acids 65 to 74 and 193 to 216. The truncated mutant Δ65-74 exhibited markedly reduced activity toward 2,4-DNBA, but its 2-NBA reduction activity was unaffected; however, both activities were abolished in the Δ193-216 mutant, suggesting that these regions are necessary for the catalysis and specificity of NbaA. NbaA showed different lag times for the reduction of 2-NBA and 2,4-DNBA with NADPH, and the reduction of 2,4-DNBA, but not 2-NBA, failed in the presence of 1 mM dithiothreitol or under anaerobic conditions, indicating oxidative modification of the enzyme for 2,4-DNBA. The enzyme was irreversibly inhibited by 5,5'-dithio-bis-(2-nitrobenzoic acid) and ZnCl(2), which bind to reactive thiol/thiolate groups, and was eventually inactivated during the formation of higher-order oligomers at high pH, high temperature, or in the presence of H(2)O(2). SDS-PAGE and mass spectrometry revealed the formation of intermolecular disulfide bonds by involvement of the two cysteines at positions 141 and 194. Site-directed mutagenesis indicated that the cysteines at positions 39, 103, 141, and 194 played a role in changing the enzyme activity and specificity toward 2-NBA and 2,4-DNBA. This study suggests that oxidative modifications of NbaA are responsible for the differential specificity for the two substrates and further enzyme inactivation through the formation of disulfide bonds under oxidizing conditions.


Assuntos
Nitrobenzoatos/metabolismo , Nitrorredutases/metabolismo , Pseudomonas fluorescens/enzimologia , Sequência de Aminoácidos , Dissulfetos/metabolismo , Eletroforese em Gel de Poliacrilamida , Peróxido de Hidrogênio , Concentração de Íons de Hidrogênio , Espectrometria de Massas , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , NADP/metabolismo , Nitrorredutases/genética , Oxirredução , Deleção de Sequência , Homologia de Sequência de Aminoácidos , Especificidade por Substrato , Temperatura
14.
Acta Crystallogr D Biol Crystallogr ; 69(Pt 10): 1867-75, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24100307

RESUMO

CueP was initially identified as a copper-resistance gene in Salmonella enterica serovar Typhimurium, which has evolved to survive in the phagosomes of macrophages. Recently, CueP was determined to be a periplasmic copper-binding protein and has been implicated in the transfer of copper ions to SodCII in the periplasm. In this study, the crystal structure of CueP has been determined, revealing a V-shaped dimeric structure. The conserved cysteine and histidine residues are clustered on the surface of one side of the C-terminal domain, suggesting that this cysteine- and histidine-rich region is related to the function of CueP. LC-MS/MS analysis established the presence of a disulfide bond between Cys96 and Cys176 under aerobic conditions. Subsequent biophysical analyses showed that the CueP protein binds copper and zinc, and the mutation of Cys104 to serine (C104S) dramatically reduced the binding affinity for copper and zinc, suggesting that the cysteine- and histidine-rich cluster is responsible for copper binding. This study provides a structural basis for the participation of CueP in the resistance of the intracellular pathogen Salmonella to copper.


Assuntos
Proteínas de Bactérias/química , Proteínas de Transporte/química , Cobre/química , Proteínas Periplásmicas de Ligação/química , Salmonella typhimurium/química , Animais , Proteínas de Bactérias/metabolismo , Proteínas de Transporte/metabolismo , Cobre/metabolismo , Cristalização , Cristalografia por Raios X , Humanos , Proteínas Periplásmicas de Ligação/metabolismo , Multimerização Proteica , Salmonella typhimurium/metabolismo , Salmonella typhimurium/patogenicidade
15.
J Proteome Res ; 11(6): 3219-30, 2012 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-22564194

RESUMO

The effects of redox-sensitive proteins on Escherichia coli were investigated by overexpressing Pseudomonas 2-nitrobenzoate nitroreductase (NbaA) and its mutants. Overexpression of wild-type and mutant NbaA proteins significantly altered the sensitivity of E. coli to antibiotics and reactive oxygen species regardless of the enzyme activity for reduction of 2-nitrobenzoic acid. The overexpressed proteins rendered cells 100-10000-fold more sensitive to superoxide anion (O2(•-))-generating paraquat and 10-100-fold more resistant to H2O2. A significant increase in intracellular levels of O2(•-), but not H2O2, was observed during expression of wild-type and truncated (Δ65-74, Δ193-216, and Δ65-74Δ193-216) NbaA. From two-dimensional nonreducing/reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry analyses, 29 abundant proteins in the cytoplasm were identified to form interchain disulfide bonds, when cells were exposed to polymyxin B. Of them, down-regulation and modifications of SodB, KatE, and KatG were strongly associated with elevated cellular O2(•-) levels. Western blotting showed up-regulation of cell death signal sensor, CpxA, and down-regulation of cytoplasmic superoxide dismutase, SodB, with ∼2-fold up-regulation of heterodimeric integration host factor, Ihf. Activity gel assays revealed significant reduction of glyceraldehyde-3-phosphate dehydrogenase with constant levels of 6-phosphogluconate dehydrogenase. These changes would support a high level of NADPH to reduce H2O2-induced disulfide bonds by forced expression of thioredoxin A via thioredoxin reductase. Thus, overexpression of wild-type and truncated NbaA partially compensates for the lack of KatE and KatG to degrade H2O2, thereby enhancing disulfide bond formation in the cytoplasm, and modifies a regulatory network of disulfide-bonded proteins to increase intracellular O2(•-) levels.


Assuntos
Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Nitrorredutases/genética , Espécies Reativas de Oxigênio/farmacologia , Substituição de Aminoácidos , Antibacterianos/farmacologia , Cistina/metabolismo , Regulação para Baixo , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Expressão Gênica , Cinética , Redes e Vias Metabólicas , Testes de Sensibilidade Microbiana , Nitrorredutases/biossíntese , Nitrorredutases/química , Oxirredução , Estresse Oxidativo , Mapas de Interação de Proteínas , Pseudomonas/enzimologia , Espécies Reativas de Oxigênio/metabolismo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Regulação para Cima
16.
J Microbiol ; 60(4): 411-418, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35286604

RESUMO

Bacillus velezensis strain GH1-13 contains a (2R,3R)-butanediol dehydrogenase (R-BDH) BdhA which converts acetoin to R-BD reversibly, however, little is known about its regulatory cysteine and biological significance. We performed site-directed mutation of three cysteines in BdhA. The C37S mutant had no enzyme activity and the C34S and C177S mutants differed from each other and wild type (WT). After zinc affinity chromatography, 1 mM ZnCl2 treatment resulted in a 3-fold enhancement of the WT activity, but reduced activity of the C34S mutant by more than 2 folds compared to the untreated ones. However, ZnCl2 treatment did not affect the activity of the C177S mutant. Most of the double and triple mutant proteins (C34S/C37S, C34S/C177S, C37S/C177S, and C34S/C37S/C177S) were aggregated in zinc resins, likely due to the decreased protein stability. All of the purified WT and single mutant proteins increased multiple intermolecular disulfide bonds in the presence of H2O2 as the buffer pH decreased from 7.5 to 5.5, whereas an intramolecular disulfide bond of cysteine 177 and another cysteine in the CGIC motif region was likely formed at pH higher than pKa of 7.5. When pH varied, WT and its C34S or C177S mutants reduced acetoin to R-BD at the optimum pH 5.5 and oxidized R-BD to acetoin at the optimum pH 10. This study demonstrated that cysteine residues in BdhA play a regulatory role for the production of acetoin and R-BD depending on pH as well as metal binding and oxidative stress.


Assuntos
Butileno Glicóis , Cisteína , Oxirredutases do Álcool , Bacillus , Butileno Glicóis/química , Butileno Glicóis/metabolismo , Peróxido de Hidrogênio
17.
Acta Crystallogr D Struct Biol ; 78(Pt 1): 104-112, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34981766

RESUMO

The YxaL protein was isolated from the soil bacterium Bacillus velezensis and has been shown to promote the root growth of symbiotic plants. YxaL has further been suggested to act as an exogenous signaling protein to induce the growth and branching of plant roots. Amino acid sequence analysis predicted YxaL to exhibit an eight-bladed ß-propeller fold stabilized by six tryptophan-docking motifs and two modified motifs. Protein engineering to improve its structural stability is needed to increase the utility of YxaL as a plant growth-promoting factor. Here, the crystal structure of YxaL from B. velezensis was determined at 1.8 Šresolution to explore its structural features for structure-based protein engineering. The structure showed the typical eight-bladed ß-propeller fold with structural variations in the third and fourth blades, which may decrease the stability of the ß-propeller fold. Engineered proteins targeting the modified motifs were subsequently created. Crystal structures of the engineered YxaL proteins showed that the typical tryptophan-docking interaction was restored in the third and fourth blades, with increased structural stability, resulting in improved root growth-promoting activity in Arabidopsis seeds. The work is an example of structure-based protein engineering to improve the structural stability of ß-propellor fold proteins.


Assuntos
Bacillus/química , Reguladores de Crescimento de Plantas/química , Engenharia de Proteínas/métodos , Bacillus/genética , Cristalografia por Raios X , Modelos Moleculares , Estrutura Molecular , Mutagênese Sítio-Dirigida , Domínios e Motivos de Interação entre Proteínas , Triptofano/química
18.
J Microbiol ; 60(8): 795-805, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35835959

RESUMO

Hydrogen peroxide (H2O2) is produced by alpha-hemolytic streptococci in aerobic conditions. However, the suitable method for detection of H2O2-producing streptococci in oral microbiota has not been setup. Here we show that o-dianisidine dye and horseradish peroxidase were useful in tryptic soy agar medium to detect and isolate H2O2-producing bacteria with the detection limit of one target colony in > 106 colony-forming units. As a proof, we isolated the strain HP01 (KCTC 21190) from a saliva sample using the medium and analyzed its characteristics. Further tests showed that the strain HP01 belongs to Streptococcus oralis in the Mitis group and characteristically forms short-chain streptococcal cells with a high capacity of acid tolerance and biofilm formation. The genome analysis revealed divergence of the strain HP01 from the type strains of S. oralis. They showed distinctive phylogenetic distances in their ROS-scavenging proteins, including superoxide dismutase SodA, thioredoxin TrxA, thioredoxin reductase TrxB, thioredoxin-like protein YtpP, and glutaredoxin-like protein NrdH, as well as a large number of antimicrobial resistance genes and horizontally transferred genes. The concatenated ROS-scavenging protein sequence can be used to identify and evaluate Streptococcus species and subspecies based on phylogenetic analysis.


Assuntos
Peróxido de Hidrogênio , Streptococcus oralis , Peróxido de Hidrogênio/metabolismo , Filogenia , Espécies Reativas de Oxigênio/metabolismo , Saliva , Streptococcus/genética , Streptococcus/metabolismo , Streptococcus oralis/genética , Streptococcus oralis/metabolismo , Tiorredoxinas/genética , Tiorredoxinas/metabolismo
19.
Atherosclerosis ; 357: 1-8, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35981436

RESUMO

BACKGROUND AND AIMS: Data on the long-term effects of everolimus (EVL) on the de novo immunosuppression of heart transplant (HT) recipients with progressive cardiac allograft vasculopathy (CAV) and vascular remodeling are lacking. Hence, in this study, we aimed to determine the long-term safety and efficacy of EVL as a de novo immunosuppressant therapy for CAV progression and the clinical outcomes after HT. METHODS: We retrospectively reviewed the medical records of 144 HT recipients who survived for at least one year after HT. CAV progression was assessed via serial coronary intravascular ultrasonography (IVUS) in recipients who underwent at least two IVUS studies. RESULTS: A significant attenuation in the percentage of the atheroma volume progression was observed in those who took EVL (1.2%) compared with those who took cyclosporin (CSA; 7.3%; p = 0.005 vs. EVL) or tacrolimus (TAC; 6.6%; p = 0.0052 vs. EVL) at 1 year after HT. This trend persisted for the next 3 and 5 years after HT. Moreover, the remodeling index was greater in the EVL (1.08) group than in the CSA (0.23) or TAC (-0.25) groups 1 year after HT. The results of the Kaplan-Meier analysis over a median follow-up period of 8 years revealed that there was no statistical difference in the primary endpoint between the three groups. CONCLUSIONS: De novo immunosuppression with EVL is associated with attenuated CAV progression for the first 5 years of follow-up via IVUS. Moreover, EVL has comparable long-term clinical outcomes to those of CSA- or TAC-based protocols.


Assuntos
Cardiopatias , Transplante de Coração , Aloenxertos , Everolimo/efeitos adversos , Seguimentos , Transplante de Coração/efeitos adversos , Humanos , Imunossupressores/efeitos adversos , Estudos Retrospectivos , Sirolimo , Ultrassonografia de Intervenção
20.
Microb Ecol ; 62(3): 725-37, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21409344

RESUMO

Compost has been widely used in order to promote vegetation growth in post-harvested and burned soils. The effects on soil microorganisms were scarcely known, so we performed the microbial analyses in a wildfire area of the Taebaek Mountains, Korea, during field surveys from May to September 2007. Using culture-dependent and -independent methods, we found that compost used in burned soils influenced a greater impact on soil fungi than bacteria. Compost-treated soils contained higher levels of antifungal strains in the genera Bacillus and Burkholderia than non-treated soils. When the antifungal activity of Burkholderia sp. strain O1a_RA002, which had been isolated from a compost-treated soil, was tested for the growth inhibition of bacteria and fungi isolated from burned soils, the membrane-filtered culture supernatant inhibited 19/37 fungal strains including soil fungi, Eupenicillium spp. and Devriesia americana; plant pathogens, Polyschema larviformis and Massaria platani; an animal pathogen, Mortierella verticillata; and an unidentified Ascomycota. However, this organism only inhibited 11/151 bacterial strains tested. These patterns were compatible with the culture-independent DGGE results, suggesting that the compost used in burned soils had a greater impact on soil fungi than bacteria through the promotion of the growth of antifungal bacteria. Our findings indicate that compost used in burned soils is effective in restoring soil conditions to a state closer to those of nearby unburned forest soils at the early stage of secondary succession.


Assuntos
Antibiose , Bactérias/isolamento & purificação , Incêndios , Fungos/isolamento & purificação , Microbiologia do Solo , Árvores/microbiologia , Contagem de Colônia Microbiana , República da Coreia , Solo/análise
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa