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1.
FASEB J ; 38(11): e23724, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38837712

RESUMO

Mycobacterium tuberculosis, the pathogen of the deadly disease tuberculosis, depends on the redox cofactor mycofactocin (MFT) to adapt to and survive under hypoxic conditions. MftR is a TetR family transcription regulator that binds upstream of the MFT gene cluster and controls MFT synthesis. To elucidate the structural basis underlying MftR regulation, we determined the crystal structure of Mycobacterium tuberculosis MftR (TB-MftR). The structure revealed an interconnected hydrogen bond network in the α1-α2-α3 helices of helix-turn-helix (HTH) DNA-binding domain that is essential for nucleic acid interactions. The ligand-binding domain contains a hydrophobic cavity enclosing long-chain fatty acyl-CoAs like the key regulatory ligand oleoyl-CoA. Despite variations in ligand-binding modes, comparative analyses suggest regulatory mechanisms are largely conserved across TetR family acyl-CoA sensors. By elucidating the intricate structural mechanisms governing DNA and ligand binding by TB-MftR, our study enhances understanding of the regulatory roles of this transcription factor under hypoxic conditions, providing insights that could inform future research into Mycobacterium tuberculosis pathogenesis.


Assuntos
Proteínas de Bactérias , Mycobacterium tuberculosis , Mycobacterium tuberculosis/metabolismo , Mycobacterium tuberculosis/genética , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica , Cristalografia por Raios X , Fatores de Transcrição/metabolismo , Fatores de Transcrição/química , Fatores de Transcrição/genética , Modelos Moleculares , Sequência de Aminoácidos
2.
Proc Natl Acad Sci U S A ; 121(24): e2401686121, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38838019

RESUMO

S-layers are crystalline arrays found on bacterial and archaeal cells. Lactobacillus is a diverse family of bacteria known especially for potential gut health benefits. This study focuses on the S-layer proteins from Lactobacillus acidophilus and Lactobacillus amylovorus common in the mammalian gut. Atomic resolution structures of Lactobacillus S-layer proteins SlpA and SlpX exhibit domain swapping, and the obtained assembly model of the main S-layer protein SlpA aligns well with prior electron microscopy and mutagenesis data. The S-layer's pore size suggests a protective role, with charged areas aiding adhesion. A highly similar domain organization and interaction network are observed across the Lactobacillus genus. Interaction studies revealed conserved binding areas specific for attachment to teichoic acids. The structure of the SlpA S-layer and the suggested incorporation of SlpX as well as its interaction with teichoic acids lay the foundation for deciphering its role in immune responses and for developing effective treatments for a variety of infectious and bacteria-mediated inflammation processes, opening opportunities for targeted engineering of the S-layer or lactobacilli bacteria in general.


Assuntos
Glicoproteínas de Membrana , Ácidos Teicoicos , Ácidos Teicoicos/metabolismo , Ácidos Teicoicos/química , Glicoproteínas de Membrana/metabolismo , Glicoproteínas de Membrana/química , Lactobacillus/metabolismo , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Modelos Moleculares , Lactobacillus acidophilus/metabolismo , Lactobacillus acidophilus/genética
3.
Open Biol ; 14(6): 230448, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38862016

RESUMO

Gram-negative bacteria from the Bacteroidota phylum possess a type-IX secretion system (T9SS) for protein secretion, which requires cargoes to have a C-terminal domain (CTD). Structurally analysed CTDs are from Porphyromonas gingivalis proteins RgpB, HBP35, PorU and PorZ, which share a compact immunoglobulin-like antiparallel 3+4 ß-sandwich (ß1-ß7). This architecture is essential as a P. gingivalis strain with a single-point mutant of RgpB disrupting the interaction of the CTD with its preceding domain prevented secretion of the protein. Next, we identified the C-terminus ('motif C-t.') and the loop connecting strands ß3 and ß4 ('motif Lß3ß4') as conserved. We generated two strains with insertion and replacement mutants of PorU, as well as three strains with ablation and point mutants of RgpB, which revealed both motifs to be relevant for T9SS function. Furthermore, we determined the crystal structure of the CTD of mirolase, a cargo of the Tannerella forsythia T9SS, which shares the same general topology as in Porphyromonas CTDs. However, motif Lß3ß4 was not conserved. Consistently, P. gingivalis could not properly secrete a chimaeric protein with the CTD of peptidylarginine deiminase replaced with this foreign CTD. Thus, the incompatibility of the CTDs between these species prevents potential interference between their T9SSs.


Assuntos
Proteínas de Bactérias , Sistemas de Secreção Bacterianos , Porphyromonas gingivalis , Porphyromonas gingivalis/metabolismo , Porphyromonas gingivalis/genética , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Sistemas de Secreção Bacterianos/metabolismo , Sistemas de Secreção Bacterianos/genética , Sistemas de Secreção Bacterianos/química , Modelos Moleculares , Cristalografia por Raios X , Sequência de Aminoácidos , Sinais Direcionadores de Proteínas , Domínios Proteicos , Bacteroidetes/metabolismo , Bacteroidetes/genética , Tannerella forsythia/metabolismo , Tannerella forsythia/genética , Tannerella forsythia/química , Relação Estrutura-Atividade , Conformação Proteica
4.
Nat Commun ; 15(1): 4912, 2024 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-38851738

RESUMO

Bacterial adhesion is a fundamental process which enables colonisation of niche environments and is key for infection. However, in Legionella pneumophila, the causative agent of Legionnaires' disease, these processes are not well understood. The Legionella collagen-like protein (Lcl) is an extracellular peripheral membrane protein that recognises sulphated glycosaminoglycans on the surface of eukaryotic cells, but also stimulates bacterial aggregation in response to divalent cations. Here we report the crystal structure of the Lcl C-terminal domain (Lcl-CTD) and present a model for intact Lcl. Our data reveal that Lcl-CTD forms an unusual trimer arrangement with a positively charged external surface and negatively charged solvent exposed internal cavity. Through molecular dynamics simulations, we show how the glycosaminoglycan chondroitin-4-sulphate associates with the Lcl-CTD surface via distinct binding modes. Our findings show that Lcl homologs are present across both the Pseudomonadota and Fibrobacterota-Chlorobiota-Bacteroidota phyla and suggest that Lcl may represent a versatile carbohydrate-binding mechanism.


Assuntos
Proteínas de Bactérias , Colágeno , Glicosaminoglicanos , Legionella pneumophila , Simulação de Dinâmica Molecular , Ligação Proteica , Glicosaminoglicanos/metabolismo , Glicosaminoglicanos/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Legionella pneumophila/metabolismo , Colágeno/metabolismo , Colágeno/química , Cristalografia por Raios X , Sulfatos de Condroitina/metabolismo , Sulfatos de Condroitina/química , Aderência Bacteriana , Domínios Proteicos , Doença dos Legionários/microbiologia , Doença dos Legionários/metabolismo , Humanos , Sequência de Aminoácidos
5.
Carbohydr Polym ; 340: 122295, 2024 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-38858006

RESUMO

GH30 xylobiohydrolases, an expanding enzyme category, need deeper insights for optimal use. The primary aim of this study was to characterize a new xylobiohydrolase, AcGH30A of GH30 family from Acetivibrio clariflavus. The gene encoding AcGH30A was cloned using pET28a(+) vector and expressed in E. coli BL21(DE3) cells. AcGH30A was purified by immobilized metal-ion affinity chromatography. SDS-PAGE analysis of AcGH30A showed molecular mass of ~58 kDa. AcGH30A showed optimum temperature 80 °C and optimum pH 7.0. AcGH30A was stable (maintaining >80 % of control activity) in pH range, 4-7 and temperature range, 30 °C -70 °C when incubated for 90 min. AcGH30A displayed melting temperature, 72 °C and half-life, 21 days at 4 °C. The enzyme activity of AcGH30A was enhanced by 10 mM Ca2+ and Mg2+ ions by 25 % and 21 %, respectively, whereas 10 mM Co2+, Zn2+, Fe2+, and Cu2+ ions significantly reduced it. AcGH30A showed activity against various xylan polysaccharides displaying highest Vmax, 139 U.mg-1 and KM, 0.71 mg.ml-1 against 4-O-methyl glucuronoxylan under optimum conditions. TLC, HPLC and LC-MS analyses of AcGH30A hydrolyzed products from xylan substrates revealed the release of sole product, xylobiose, confirming it as an obligate xylobiohydrolase. AcGH30A being a highly thermostable enzyme can be potentially utlilized in various biotechnological applications.


Assuntos
Estabilidade Enzimática , Proteínas Recombinantes , Xilanos , Xilanos/química , Xilanos/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Concentração de Íons de Hidrogênio , Temperatura , Especificidade por Substrato , Hidrólise , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/isolamento & purificação , Clonagem Molecular , Escherichia coli/genética
6.
Nat Commun ; 15(1): 4852, 2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38844755

RESUMO

A short prokaryotic Argonaute (pAgo) TIR-APAZ (SPARTA) defense system, activated by invading DNA to unleash its TIR domain for NAD(P)+ hydrolysis, was recently identified in bacteria. We report the crystal structure of SPARTA heterodimer in the absence of guide-RNA/target-ssDNA (2.66 Å) and a cryo-EM structure of the SPARTA oligomer (tetramer of heterodimers) bound to guide-RNA/target-ssDNA at nominal 3.15-3.35 Å resolution. The crystal structure provides a high-resolution view of SPARTA, revealing the APAZ domain as equivalent to the N, L1, and L2 regions of long pAgos and the MID domain containing a unique insertion (insert57). Cryo-EM structure reveals regions of the PIWI (loop10-9) and APAZ (helix αN) domains that reconfigure for nucleic-acid binding and decrypts regions/residues that reorganize to expose a positively charged pocket for higher-order assembly. The TIR domains amass in a parallel-strands arrangement for catalysis. We visualize SPARTA before and after RNA/ssDNA binding and uncover the basis of its active assembly leading to abortive infection.


Assuntos
Proteínas Argonautas , Microscopia Crioeletrônica , Proteínas Argonautas/metabolismo , Proteínas Argonautas/química , Proteínas Argonautas/genética , Cristalografia por Raios X , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Domínios Proteicos , DNA de Cadeia Simples/metabolismo , DNA de Cadeia Simples/química , RNA Guia de Sistemas CRISPR-Cas/metabolismo , Modelos Moleculares , Ácidos Nucleicos/metabolismo , Ácidos Nucleicos/química , Ligação Proteica
7.
Methods Mol Biol ; 2796: 1-21, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38856892

RESUMO

Cell membranes are highly intricate systems comprising numerous lipid species and membrane proteins, where channel proteins, lipid molecules, and lipid bilayers, as continuous elastic fabric, collectively engage in multi-modal interplays. Owing to the complexity of the native cell membrane, studying the elementary processes of channel-membrane interactions necessitates a bottom-up approach starting from forming simplified synthetic membranes. This is the rationale for establishing an in vitro membrane reconstitution system consisting of a lipid bilayer with a defined lipid composition and a channel molecule. Recent technological advancements have facilitated the development of asymmetric membranes, and the contact bubble bilayer (CBB) method allows single-channel current recordings under arbitrary lipid compositions in asymmetric bilayers. Here, we present an experimental protocol for the formation of asymmetric membranes using the CBB method. The KcsA potassium channel is a prototypical model channel with huge structural and functional information and thus serves as a reporter of membrane actions on the embedded channels. We demonstrate specific interactions of anionic lipids in the inner leaflet. Considering that the local lipid composition varies steadily in cell membranes, we `present a novel lipid perfusion technique that allows rapidly changing the lipid composition while monitoring the single-channel behavior. Finally, we demonstrate a leaflet perfusion method for modifying the composition of individual leaflets. These techniques with custom synthetic membranes allow for variable experiments, providing crucial insights into channel-membrane interplay in cell membranes.


Assuntos
Bicamadas Lipídicas , Canais de Potássio , Bicamadas Lipídicas/química , Bicamadas Lipídicas/metabolismo , Canais de Potássio/química , Canais de Potássio/metabolismo , Membrana Celular/metabolismo , Membrana Celular/química , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo
8.
Methods Mol Biol ; 2796: 35-72, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38856894

RESUMO

Fluorescence techniques have been widely used to shed light over the structure-function relationship of potassium channels for the last 40-50 years. In this chapter, we describe how a Förster resonance energy transfer between identical fluorophores (homo-FRET) approach can be applied to study the gating behavior of the prokaryotic channel KcsA. Two different gates have been described to control the K+ flux across the channel's pore, the helix-bundle crossing and the selectivity filter, located at the opposite sides of the channel transmembrane section. Both gates can be studied individually or by using a double-reporter system. Due to its homotetrameric structural arrangement, KcsA presents a high degree of symmetry that fulfills the first requisite to calculate intersubunit distances through this technique. The results obtained through this work have helped to uncover the conformational plasticity of the selectivity filter under different experimental conditions and the importance of its allosteric coupling to the opening of the activation (inner) gate. This biophysical approach usually requires low protein concentration and presents high sensitivity and reproducibility, complementing the high-resolution structural information provided by X-ray crystallography, cryo-EM, and NMR studies.


Assuntos
Proteínas de Bactérias , Transferência Ressonante de Energia de Fluorescência , Canais de Potássio , Conformação Proteica , Transferência Ressonante de Energia de Fluorescência/métodos , Canais de Potássio/metabolismo , Canais de Potássio/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Ativação do Canal Iônico , Modelos Moleculares
9.
Curr Microbiol ; 81(7): 211, 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38839629

RESUMO

This study aimed to obtain reliable high Vip3A production from Bacillus thuringiensis (Bt) by modifying Vip3A to acquire higher thermostability in a suitable host. Bt117 is a great host for Vip3A production due to protein production consistency, low protease activity in culture media, and large amounts of mostly full-length protein, but it produces Vip3A with lower thermostability (Vip3Aa35). The C-terminal region of Bt117 Vip3A was replaced with that of a Vip3A with higher thermostability (Vip3Aa64 from Bt294) to generate the recombinant Bt117-Vip3Aa64-C. Like the parental strain Bt117, this strain expressed mostly full-length protein and exhibited low protease activity and similar protein expression profiles in culture media but retained greater larvicidal activity upon 37 °C storage like Bt294 Vip3Aa64. Importantly, every culture batch of Bt117-Vip3Aa64-C yielded over 200 mg/l Vip3A, which is a notable improvement over the original Vip3Aa64-producing strain Bt294 where 45% of culture batches failed to produce Vip3A at the same level. Successfully, we combined the superior qualities of two Bt strains, Bt294, which produces thermostable Vip3A but at low and inconsistent levels, and Bt117, which produces Vip3A with low thermostability but at consistently high levels. Protein engineering of Vip3A in Bt117 ultimately yielded an improved strain producing a thermostable Vip3A with reliably high protein production.


Assuntos
Bacillus thuringiensis , Proteínas de Bactérias , Engenharia de Proteínas , Bacillus thuringiensis/genética , Bacillus thuringiensis/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Animais , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/química , Larva/microbiologia , Estabilidade Proteica
10.
Sci Rep ; 14(1): 12876, 2024 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-38834612

RESUMO

This study investigates quercetin complexes as potential synergistic agents against the important respiratory pathogen Streptococcus pneumoniae. Six quercetin complexes (QCX1-6) were synthesized by reacting quercetin with various metal salts and boronic acids and characterized using FTIR spectroscopy. Their antibacterial activity alone and in synergism with antibiotics was evaluated against S. pneumoniae ATCC 49619 using disc diffusion screening, broth microdilution MIC determination, and checkerboard assays. Complexes QCX-3 and QCX-4 demonstrated synergy when combined with levofloxacin via fractional inhibitory concentration indices ≤ 0.5 as confirmed by time-kill kinetics. Molecular docking elucidated interactions of these combinations with virulence enzymes sortase A and sialidase. A biofilm inhibition assay found the synergistic combinations more potently reduced biofilm formation versus monotherapy. Additionally, gene-gene interaction networks, biological activity predictions and in-silico toxicity profiling provided insights into potential mechanisms of action and safety.


Assuntos
Antibacterianos , Biofilmes , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Quercetina , Streptococcus pneumoniae , Streptococcus pneumoniae/efeitos dos fármacos , Quercetina/farmacologia , Quercetina/química , Antibacterianos/farmacologia , Antibacterianos/química , Biofilmes/efeitos dos fármacos , Sinergismo Farmacológico , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/antagonistas & inibidores , Cisteína Endopeptidases/metabolismo , Cisteína Endopeptidases/química , Aminoaciltransferases/antagonistas & inibidores , Aminoaciltransferases/metabolismo , Neuraminidase/antagonistas & inibidores , Neuraminidase/metabolismo
11.
Appl Microbiol Biotechnol ; 108(1): 365, 2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38842543

RESUMO

Lipases are important biocatalysts and ubiquitous in plants, animals, and microorganisms. The high growth rates of microorganisms with low production costs have enabled the wide application of microbial lipases in detergent, food, and cosmetic industries. Herein, a novel lipase from Lacticaseibacillus rhamnosus IDCC 3201 (Lac-Rh) was isolated and its activity analyzed under a range of reaction conditions to evaluate its potential industrial application. The isolated Lac-Rh showed a molecular weight of 24 kDa and a maximum activity of 3438.5 ± 1.8 U/mg protein at 60 °C and pH 8. Additionally, Lac-Rh retained activity in alkaline conditions and in 10% v/v concentrations of organic solvents, including glycerol and acetone. Interestingly, after pre-incubation in the presence of multiple commercial detergents, Lac-Rh maintained over 80% of its activity and the stains from cotton were successfully removed under a simulated laundry  setting. Overall, the purified lipase from L. rhamnosus IDCC 3201 has potential for use as a detergent in industrial applications. KEY POINTS: • A novel lipase (Lac-Rh) was isolated from Lacticaseibacillus rhamnosus IDCC 3201 • Purified Lac-Rh exhibited its highest activity at a temperature of 60 °C and a pH of 8, respectively • Lac-Rh remains stable in commercial laundry detergent and enhances washing performance.


Assuntos
Detergentes , Estabilidade Enzimática , Lacticaseibacillus rhamnosus , Lipase , Lipase/metabolismo , Lipase/química , Lipase/genética , Lacticaseibacillus rhamnosus/enzimologia , Lacticaseibacillus rhamnosus/genética , Lacticaseibacillus rhamnosus/química , Concentração de Íons de Hidrogênio , Detergentes/química , Temperatura , Peso Molecular , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo
12.
Nat Commun ; 15(1): 4850, 2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38844782

RESUMO

Bacterial RNAP needs to form holoenzyme with σ factors to initiate transcription. While Staphylococcus aureus σA controls housekeeping functions, S. aureus σB regulates virulence, biofilm formation, persistence, cell internalization, membrane transport, and antimicrobial resistance. Besides the sequence difference, the spacers between the -35 element and -10 element of σB regulated promoters are shorter than those of σA regulated promoters. Therefore, how σB recognizes and initiates transcription from target promoters can not be inferred from that of the well studied σ. Here, we report the cryo-EM structures of S. aureus RNAP-promoter open complexes comprising σA and σB, respectively. Structural analyses, in combination with biochemical experiments, reveal the structural basis for the promoter specificity of S. aureus transcription. Although the -10 element of σA regulated promoters is recognized by domain σA2 as single-stranded DNA, the -10 element of σB regulated promoters is co-recognized by domains σB2 and σB3 as double-stranded DNA, accounting for the short spacers of σB regulated promoters. S. aureus RNAP is a validated target of antibiotics, and our structures pave the way for rational drug design targeting S. aureus RNAP.


Assuntos
Proteínas de Bactérias , Microscopia Crioeletrônica , RNA Polimerases Dirigidas por DNA , Regiões Promotoras Genéticas , Fator sigma , Staphylococcus aureus , Staphylococcus aureus/genética , Staphylococcus aureus/enzimologia , RNA Polimerases Dirigidas por DNA/metabolismo , RNA Polimerases Dirigidas por DNA/genética , RNA Polimerases Dirigidas por DNA/química , Fator sigma/metabolismo , Fator sigma/genética , Fator sigma/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Regulação Bacteriana da Expressão Gênica , Modelos Moleculares , Transcrição Gênica , Ligação Proteica
13.
Protein Sci ; 33(7): e5025, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38864689

RESUMO

Polyhydroxyalkanoates are a class of biodegradable, thermoplastic polymers which represent a major carbon source for various bacteria. Proteins which mediate the translocation of polyhydroxyalkanoate breakdown products, such as ß-hydroxybutyrate (BHB)-a ketone body which in humans serves as an important biomarker, have not been well characterized. In our investigation to screen a solute-binding protein (SBP) which can act as a suitable recognition element for BHB, we uncovered insights at the intersection of bacterial metabolism and diagnostics. Herein, we identify SBPs associated with putative ATP-binding cassette transporters that specifically recognize BHB, with the potential to serve as recognition elements for continuous quantification of this analyte. Through bioinformatic analysis, we identified candidate SBPs from known metabolizers of polyhydroxybutyrate-including proteins from Cupriavidus necator, Ensifer meliloti, Paucimonas lemoignei, and Thermus thermophilus. After recombinant expression in Escherichia coli, we demonstrated with intrinsic tryptophan fluorescence spectroscopy that four candidate proteins interacted with BHB, ranging from nanomolar to micromolar affinity. Tt.2, an intrinsically thermostable protein from Thermus thermophilus, was observed to have the tightest binding and specificity for BHB, which was confirmed by isothermal calorimetry. Structural analyses facilitated by AlphaFold2, along with molecular docking and dynamics simulations, were used to hypothesize key residues in the binding pocket and to model the conformational dynamics of substrate unbinding. Overall, this study provides strong evidence identifying the cognate ligands of SBPs which we hypothesize to be involved in prokaryotic cellular translocation of polyhydroxyalkanoate breakdown products, while highlighting these proteins' promising biotechnological application.


Assuntos
Ácido 3-Hidroxibutírico , Ácido 3-Hidroxibutírico/metabolismo , Ácido 3-Hidroxibutírico/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas Periplásmicas de Ligação/metabolismo , Proteínas Periplásmicas de Ligação/química , Proteínas Periplásmicas de Ligação/genética , Escherichia coli/metabolismo , Escherichia coli/genética , Corpos Cetônicos/metabolismo , Corpos Cetônicos/química
14.
Protein Sci ; 33(7): e5038, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38864725

RESUMO

Peptidoglycan is a major constituent of the bacterial cell wall. Its integrity as a polymeric edifice is critical for bacterial survival and, as such, it is a preeminent target for antibiotics. The peptidoglycan is a dynamic crosslinked polymer that undergoes constant biosynthesis and turnover. The soluble lytic transglycosylase (Slt) of Pseudomonas aeruginosa is a periplasmic enzyme involved in this dynamic turnover. Using amber-codon-suppression methodology in live bacteria, we incorporated a fluorescent chromophore into the structure of Slt. Fluorescent microscopy shows that Slt populates the length of the periplasmic space and concentrates at the sites of septation in daughter cells. This concentration persists after separation of the cells. Amber-codon-suppression methodology was also used to incorporate a photoaffinity amino acid for the capture of partner proteins. Mass-spectrometry-based proteomics identified 12 partners for Slt in vivo. These proteomics experiments were complemented with in vitro pulldown analyses. Twenty additional partners were identified. We cloned the genes and purified to homogeneity 22 identified partners. Biophysical characterization confirmed all as bona fide Slt binders. The identities of the protein partners of Slt span disparate periplasmic protein families, inclusive of several proteins known to be present in the divisome. Notable periplasmic partners (KD < 0.5 µM) include PBPs (PBP1a, KD = 0.07 µM; PBP5 = 0.4 µM); other lytic transglycosylases (SltB2, KD = 0.09 µM; RlpA, KD = 0.4 µM); a type VI secretion system effector (Tse5, KD = 0.3 µM); and a regulatory protease for alginate biosynthesis (AlgO, KD < 0.4 µM). In light of the functional breadth of its interactome, Slt is conceptualized as a hub protein within the periplasm.


Assuntos
Proteínas de Bactérias , Pseudomonas aeruginosa , Pseudomonas aeruginosa/enzimologia , Pseudomonas aeruginosa/metabolismo , Pseudomonas aeruginosa/genética , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Periplasma/metabolismo , Periplasma/enzimologia , Proteínas Periplásmicas/metabolismo , Proteínas Periplásmicas/genética , Proteínas Periplásmicas/química , Glicosiltransferases/metabolismo , Glicosiltransferases/genética , Glicosiltransferases/química , Peptidoglicano/metabolismo , Peptidoglicano/química
15.
Protein Sci ; 33(7): e5064, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38864722

RESUMO

Due to the low temperature, the Antarctic marine environment is challenging for protein functioning. Cold-adapted organisms have evolved proteins endowed with higher flexibility and lower stability in comparison to their thermophilic homologs, resulting in enhanced reaction rates at low temperatures. The Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 (PhTAC125) genome is one of the few examples of coexistence of multiple hemoglobin genes encoding, among others, two constitutively transcribed 2/2 hemoglobins (2/2Hbs), also named truncated Hbs (TrHbs), belonging to the Group II (or O), annotated as PSHAa0030 and PSHAa2217. In this work, we describe the ligand binding kinetics and their interrelationship with the dynamical properties of globin Ph-2/2HbO-2217 by combining experimental and computational approaches and implementing a new computational method to retrieve information from molecular dynamic trajectories. We show that our approach allows us to identify docking sites within the protein matrix that are potentially able to transiently accommodate ligands and migration pathways connecting them. Consistently with ligand rebinding studies, our modeling suggests that the distal heme pocket is connected to the solvent through a low energy barrier, while inner cavities play only a minor role in modulating rebinding kinetics.


Assuntos
Proteínas de Bactérias , Pseudoalteromonas , Hemoglobinas Truncadas , Pseudoalteromonas/metabolismo , Pseudoalteromonas/genética , Pseudoalteromonas/química , Cinética , Hemoglobinas Truncadas/química , Hemoglobinas Truncadas/metabolismo , Hemoglobinas Truncadas/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Simulação de Dinâmica Molecular , Regiões Antárticas , Ligantes
16.
Protein Sci ; 33(7): e5073, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38864770

RESUMO

A common evolutionary mechanism in biology to drive function is protein oligomerization. In prokaryotes, the symmetrical assembly of repeating protein units to form homomers is widespread, yet consideration in vitro of whether such assemblies have functional or mechanistic consequences is often overlooked. Dye-decolorizing peroxidases (DyPs) are one such example, where their dimeric α + ß barrel units can form various oligomeric states, but the oligomer influence, if any, on mechanism and function has received little attention. In this work, we have explored the oligomeric state of three DyPs found in Streptomyces lividans, each with very different mechanistic behaviors in their reactions with hydrogen peroxide and organic substrates. Using analytical ultracentrifugation, we reveal that except for one of the A-type DyPs where only a single sedimenting species is detected, oligomer states ranging from homodimers to dodecamers are prevalent in solution. Using cryo-EM on preparations of the B-type DyP, we determined a 3.02 Å resolution structure of a hexamer assembly that corresponds to the dominant oligomeric state in solution as determined by analytical ultracentrifugation. Furthermore, cryo-EM data detected sub-populations of higher-order oligomers, with one of these formed by an arrangement of two B-type DyP hexamers to give a dodecamer assembly. Our solution and structural insights of these oligomer states provide a new framework to consider previous mechanistic studies of these DyP members and are discussed in terms of long-range electron transfer for substrate oxidation and in the "storage" of oxidizable equivalents on the heme until a two-electron donor is available.


Assuntos
Corantes , Oxirredução , Peroxidases , Multimerização Proteica , Streptomyces lividans , Streptomyces lividans/enzimologia , Peroxidases/química , Peroxidases/metabolismo , Corantes/química , Corantes/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Modelos Moleculares , Especificidade por Substrato , Microscopia Crioeletrônica , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/metabolismo
17.
PLoS Biol ; 22(6): e3002680, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38865309

RESUMO

CRISPR-Cas12a, often regarded as a precise genome editor, still requires improvements in specificity. In this study, we used a GFP-activation assay to screen 14 new Cas12a nucleases for mammalian genome editing, successfully identifying 9 active ones. Notably, these Cas12a nucleases prefer pyrimidine-rich PAMs. Among these nucleases, we extensively characterized Mb4Cas12a obtained from Moraxella bovis CCUG 2133, which recognizes a YYN PAM (Y = C or T). Our biochemical analysis demonstrates that Mb4Cas12a can cleave double-strand DNA across a wide temperature range. To improve specificity, we constructed a SWISS-MODEL of Mb4Cas12a based on the FnCas12a crystal structure and identified 8 amino acids potentially forming hydrogen bonds at the target DNA-crRNA interface. By replacing these amino acids with alanine to disrupt the hydrogen bond, we tested the influence of each mutation on Mb4Cas12a specificity. Interestingly, the F370A mutation improved specificity with minimal influence on activity. Further study showed that Mb4Cas12a-F370A is capable of discriminating single-nucleotide polymorphisms. These new Cas12a orthologs and high-fidelity variants hold substantial promise for therapeutic applications.


Assuntos
Alelos , Proteínas Associadas a CRISPR , Sistemas CRISPR-Cas , Edição de Genes , Edição de Genes/métodos , Proteínas Associadas a CRISPR/metabolismo , Proteínas Associadas a CRISPR/genética , Humanos , Endodesoxirribonucleases/metabolismo , Endodesoxirribonucleases/genética , Endodesoxirribonucleases/química , Animais , Engenharia de Proteínas/métodos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Polimorfismo de Nucleotídeo Único , Mutação , DNA/metabolismo , DNA/genética , Células HEK293
18.
Sci Adv ; 10(24): eado6169, 2024 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-38865457

RESUMO

Nitrogenase plays a key role in the global nitrogen cycle; yet, the evolutionary history of nitrogenase and, particularly, the sequence of appearance between the homologous, yet distinct NifDK (the catalytic component) and NifEN (the cofactor maturase) of the extant molybdenum nitrogenase, remains elusive. Here, we report the ability of NifEN to reduce N2 at its surface-exposed L-cluster ([Fe8S9C]), a structural/functional homolog of the M-cluster (or cofactor; [(R-homocitrate)MoFe7S9C]) of NifDK. Furthermore, we demonstrate the ability of the L-cluster-bound NifDK to mimic its NifEN counterpart and enable N2 reduction. These observations, coupled with phylogenetic, ecological, and mechanistic considerations, lead to the proposal of a NifEN-like, L-cluster-carrying protein as an ancient nitrogenase, the exploration of which could shed crucial light on the evolutionary origin of nitrogenase and related enzymes.


Assuntos
Nitrogenase , Nitrogenase/metabolismo , Nitrogenase/química , Nitrogenase/genética , Filogenia , Nitrogênio/metabolismo , Nitrogênio/química , Molibdoferredoxina/química , Molibdoferredoxina/metabolismo , Modelos Moleculares , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Fixação de Nitrogênio/genética
19.
Sci Adv ; 10(24): eadn8386, 2024 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-38865454

RESUMO

Certain cyanobacteria alter their photosynthetic light absorption between green and red, a phenomenon called complementary chromatic acclimation. The acclimation is regulated by a cyanobacteriochrome-class photosensor that reversibly photoconverts between green-absorbing (Pg) and red-absorbing (Pr) states. Here, we elucidated the structural basis of the green/red photocycle. In the Pg state, the bilin chromophore adopted the extended C15-Z,anti structure within a hydrophobic pocket. Upon photoconversion to the Pr state, the bilin is isomerized to the cyclic C15-E,syn structure, forming a water channel in the pocket. The solvation/desolvation of the bilin causes changes in the protonation state and the stability of π-conjugation at the B ring, leading to a large absorption shift. These results advance our understanding of the enormous spectral diversity of the phytochrome superfamily.


Assuntos
Luz , Cianobactérias/metabolismo , Cianobactérias/fisiologia , Aclimatação , Fotossíntese , Fitocromo/metabolismo , Fitocromo/química , Modelos Moleculares , Pigmentos Biliares/metabolismo , Pigmentos Biliares/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Luz Vermelha
20.
Sci Rep ; 14(1): 13472, 2024 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-38866811

RESUMO

Waddlia chondrophila is a possible cause of fetal death in humans. This Chlamydia-related bacterium is an emergent pathogen that causes human miscarriages and ruminant abortions, which results in financial losses. Despite the years of efforts, the underlying mechanism behind the pathogenesis of W. chondrophila is little known which hindered the development of novel treatment options. In the framework of current study, computational approaches were used to identify novel inhibitors (phytocompounds) and drug targets against W. chondrophila. At first, RNA polymerase sigma factor SigA and 3-deoxy-D-manno-octulosonic acid transferase were identified through subtractive proteomics pipeline. Afterwards, extensive docking and simulation analyses were conducted to optimize potentially novel phytocompounds by assessing their binding affinity to target proteins. A 100ns molecular dynamics simulation well complimented the compound's binding affinity and indicated strong stability of predicted compounds at the docked site. The calculation of binding free energies with MMGBSA corroborated the significant binding affinity between phytocompounds and target protein binding sites. The proposed phytocompounds may be a viable treatment option for patients infected with W. chondrophila; however, further research is required to ensure their safety.


Assuntos
Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Antibacterianos/farmacologia , Antibacterianos/química , Humanos , Chlamydiales/química , Chlamydiales/efeitos dos fármacos , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Ligação Proteica , Avaliação Pré-Clínica de Medicamentos , Farmacóforo
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