Microbiology-Sgm最新文献

{"title":"Molecular insights into the determinants of substrate specificity and efflux inhibition of the RND efflux pumps AcrB and AdeB.","authors":"Julia Wilhelm, Klaas Martinus Pos","doi":"10.1099/mic.0.001438","DOIUrl":"10.1099/mic.0.001438","url":null,"abstract":"<p><p>Gram-negative bacterial members of the Resistance Nodulation and cell Division (RND) superfamily form tripartite efflux pump systems that span the cell envelope. One of the intriguing features of the multiple drug efflux members of this superfamily is their ability to recognize different classes of antibiotics, dyes, solvents, bile salts, and detergents. This review provides an overview of the molecular mechanisms of multiple drug efflux catalysed by the tripartite RND efflux system AcrAB-TolC from <i>Eschericha coli</i>. The determinants for sequential or simultaneous multiple substrate binding and efflux pump inhibitor binding are discussed. A comparison is made with the determinants for substrate binding of AdeB from <i>Acinetobacter baumannii</i>, which acts within the AdeABC multidrug efflux system. There is an apparent general similarity between the structures of AcrB and AdeB and their substrate specificity. However, the presence of distinct conformational states and different drug efflux capacities as revealed by single-particle cryo-EM and mutational analysis suggest that the drug binding and transport features exhibited by AcrB may not be directly extrapolated to the homolog AdeB efflux pump.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10924465/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139736555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"P-type ATPase zinc transporter Rv3270 of <i>Mycobacterium tuberculosis</i> enhances multi-drug efflux activity.","authors":"Debasmita Chatterjee, Aditya Prasad Panda, A R Daya Manasi, Anindya S Ghosh","doi":"10.1099/mic.0.001441","DOIUrl":"10.1099/mic.0.001441","url":null,"abstract":"<p><p>Metal homeostasis is maintained by the uptake, storage and efflux of metal ions that are necessary for the survival of the bacterium. Homeostasis is mostly regulated by a group of transporters categorized as ABC transporters and P-type ATPases. On the other hand, efflux pumps often play a role in drug-metal cross-resistance. Here, with the help of antibiotic sensitivity, antibiotic/dye accumulation and semi-quantitative biofilm formation assessments we report the ability of Rv3270, a P-type ATPase known for its role in combating Mn²⁺ and Zn²⁺ metal ion toxicity in <i>Mycobacterium tuberculosis</i>, in influencing the extrusion of multiple structurally unrelated drugs and enhancing the biofilm formation of <i>Escherichia coli</i> and <i>Mycobacterium smegmatis.</i> Overexpression of Rv3270 increased the tolerance of host cells to norfloxacin, ofloxacin, sparfloxacin, ampicillin, oxacillin, amikacin and isoniazid. A significantly lower accumulation of norfloxacin, ethidium bromide, bocillin FL and levofloxacin in cells harbouring Rv3270 as compared to host cells indicated its role in enhancing efflux activity. Although over-expression of Rv3270 did not alter the susceptibility levels of levofloxacin, rifampicin and apramycin, the presence of a sub-inhibitory concentration of Zn²⁺ resulted in low-level tolerance towards these drugs. Of note, the expression of Rv3270 enhanced the biofilm-forming ability of the host cells strengthening its role in antimicrobial resistance. Therefore, the study indicated that the over-expression of Rv3270 enhances the drug efflux activity of the micro-organism where zinc might facilitate drug-metal cross-resistance for some antibiotics.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10924464/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139900763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mutation of <i>wbtJ</i>, a <i>N</i>-formyltransferase involved in O-antigen synthesis, results in biofilm formation, phase variation and attenuation in <i>Francisella tularensis</i>.","authors":"Kevin D Mlynek, Ronald G Toothman, Elsie E Martinez, Ju Qiu, Joshua B Richardson, Joel A Bozue","doi":"10.1099/mic.0.001437","DOIUrl":"10.1099/mic.0.001437","url":null,"abstract":"<p><p>Two clinically important subspecies, <i>Francisella tularensis</i> subsp. <i>tularensis</i> (type A) and <i>F. tularensis</i> subsp. <i>holarctica</i> (type B) are responsible for most tularaemia cases, but these isolates typically form a weak biofilm under <i>in vitro</i> conditions. Phase variation of the <i>F. tularensis</i> lipopolysaccharide (LPS) has been reported in these subspecies, but the role of variation is unclear as LPS is crucial for virulence. We previously demonstrated that a subpopulation of LPS variants can constitutively form a robust biofilm <i>in vitro,</i> but it is unclear whether virulence was affected. In this study, we show that biofilm-forming variants of both fully virulent <i>F. tularensis</i> subspecies were highly attenuated in the murine tularaemia model by multiple challenge routes. Genomic sequencing was performed on these strains, which revealed that all biofilm-forming variants contained a lesion within the <i>wbtJ</i> gene, a formyltransferase involved in O-antigen synthesis. A Δ<i>wbtJ</i> deletion mutant recapitulated the biofilm, O-antigen and virulence phenotypes observed in natural variants and could be rescued through complementation with a functional <i>wbtJ</i> gene. Since the spontaneously derived biofilm-forming isolates in this study were a subpopulation of natural variants, reversion events to the <i>wbtJ</i> gene were detected that eliminated the phenotypes associated with biofilm variants and restored virulence. These results demonstrate a role for WbtJ in biofilm formation, LPS variation and virulence of <i>F. tularensis</i>.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10924466/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139991597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Current understandings of colibactin regulation.","authors":"Emily Addington, Sofia Sandalli, Andrew J Roe","doi":"10.1099/mic.0.001427","DOIUrl":"10.1099/mic.0.001427","url":null,"abstract":"<p><p>The biosynthetic machinery for the production of colibactin is encoded by 19 genes (<i>clbA - S</i>) within the <i>pks</i> pathogenicity island harboured by many <i>E. coli</i> of the B2-phylogroup. Colibactin is a potent genotoxic metabolite which causes DNA-damage and which has potential roles in microbial competition and fitness of <i>pks</i>+ bacteria. Colibactin has also been strongly implicated in the development of colorectal cancer. Given the genotoxicity of colibactin and the metabolic cost of its synthesis, the regulatory system governing the <i>clb</i> cluster is accordingly highly complex, and many of the mechanisms remain to be elucidated. In this review we summarise the current understanding of regulation of colibactin biosynthesis by internal molecular components and how these factors are modulated by signals from the external environment.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10924459/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139693344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of novel tail-anchored membrane proteins integrated by the bacterial twin-arginine translocase.","authors":"José Jesús Gallego-Parrilla, Emmanuele Severi, Govind Chandra, Tracy Palmer","doi":"10.1099/mic.0.001431","DOIUrl":"10.1099/mic.0.001431","url":null,"abstract":"<p><p>The twin-arginine protein transport (Tat) system exports folded proteins across the cytoplasmic membranes of prokaryotes and the energy transducing-membranes of plant thylakoids and mitochondria. Proteins are targeted to the Tat machinery by N-terminal signal peptides with a conserved twin-arginine motif, and some substrates are exported as heterodimers where the signal peptide is present on one of the partner proteins. A subset of Tat substrates is found in the membrane. Tat-dependent membrane proteins usually have large globular domains and a single transmembrane helix present at the N- or C-terminus. Five Tat substrates that have C-terminal transmembrane helices have previously been characterized in the model bacterium <i>Escherichia coli</i>. Each of these is an iron-sulfur cluster-containing protein involved in electron transfer from hydrogen or formate. Here we have undertaken a bioinformatic search to identify further tail-anchored Tat substrates encoded in bacterial genomes. Our analysis has revealed additional tail-anchored iron-sulfur proteins associated in modules with either a <i>b</i>-type cytochrome or a quinol oxidase. We also identified further candidate tail-anchored Tat substrates, particularly among members of the actinobacterial phylum, that are not predicted to contain cofactors. Using reporter assays, we show experimentally that six of these have both N-terminal Tat signal peptides and C-terminal transmembrane helices. The newly identified proteins include a carboxypeptidase and a predicted protease, and four sortase substrates for which membrane integration is a prerequisite for covalent attachment to the cell wall.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10924467/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139747586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ecological dependencies and the illusion of cooperation in microbial communities.","authors":"Elze Hesse, Siobhán O'Brien","doi":"10.1099/mic.0.001442","DOIUrl":"10.1099/mic.0.001442","url":null,"abstract":"<p><p>Ecological dependencies - where organisms rely on other organisms for survival - are a ubiquitous feature of life on earth. Multicellular hosts rely on symbionts to provide essential vitamins and amino acids. Legume plants similarly rely on nitrogen-fixing rhizobia to convert atmospheric nitrogen to ammonia. In some cases, dependencies can arise via loss-of-function mutations that allow one partner to benefit from the actions of another. It is common in microbiology to label ecological dependencies between species as cooperation - making it necessary to invoke cooperation-specific frameworks to explain the phenomenon. However, in many cases, such traits are not (at least initially) cooperative, because they are not selected for because of the benefits they confer on a partner species. In contrast, dependencies in microbial communities may originate from fitness benefits gained from genomic-streamlining (i.e. Black Queen Dynamics). Here, we outline how the Black Queen Hypothesis predicts the formation of metabolic dependencies via loss-of-function mutations in microbial communities, without needing to invoke any cooperation-specific explanations. Furthermore we outline how the Black Queen Hypothesis can act as a blueprint for true cooperation as well as discuss key outstanding questions in the field. The nature of interactions in microbial communities can predict the ability of natural communities to withstand and recover from disturbances. Hence, it is vital to gain a deeper understanding of the factors driving these dynamic interactions over evolutionary time.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10924460/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139933821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microbial Primer: Bacterial growth kinetics.","authors":"Lorena T Fernández-Martínez, Arnaud Javelle, Paul A Hoskisson","doi":"10.1099/mic.0.001428","DOIUrl":"10.1099/mic.0.001428","url":null,"abstract":"<p><p>tGrowth of microorganisms and interpretation of growth data are core skills required by microbiologists. While science moves forward, it is of paramount importance that essential skills are not lost. The bacterial growth curve and the information that can gleaned from it is of great value to all of microbiology, whether this be a simple growth experiment, comparison of mutant strains or the establishment of conditions for a large-scale multi-omics experiment. Increasingly, the basics of plotting and interpreting growth curves and growth data are being overlooked. This primer article serves as a refresher for microbiologists on the fundamentals of microbial growth kinetics.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10924458/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139703893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Twists and turns: 40 years of investigating how and why bacteria swim.","authors":"Judith P Armitage","doi":"10.1099/mic.0.001432","DOIUrl":"10.1099/mic.0.001432","url":null,"abstract":"<p><p>Fifty years of research has transformed our understanding of bacterial movement from one of description, based on a limited number of electron micrographs and some low-magnification studies of cells moving towards or away from chemical effectors, to probably the best understood behavioural system in biology. We have a molecular understanding of how bacteria sense and respond to changes in their environment and detailed structural insights into the workings of one of the most complex motor structures we know of. Thanks to advances in genomics we also understand how, through evolution, different species have tuned and adapted a core shared system to optimize behaviour in their specific environment. In this review, I will highlight some of the unexpected findings we made during my over 40-year career, how those findings changed some of our understanding of bacterial behaviour and biochemistry and some of the battles to have those observations accepted.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10924463/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139742467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structure and ligand binding in the putative anti-microbial peptide transporter protein, YejA.","authors":"Bryony K Ackroyd, Eleanor J Dodson, Javeria Mehboob, Adam A Dowle, Gavin H Thomas, Anthony J Wilkinson","doi":"10.1099/mic.0.001430","DOIUrl":"10.1099/mic.0.001430","url":null,"abstract":"<p><p>YejABEF is an ATP-binding cassette transporter that is implicated in the sensitivity of <i>Escherichia coli</i> to anti-microbial peptides, the best-characterized example being microcin C, a peptide-nucleotide antibiotic that targets aspartyl-tRNA synthetase. Here the structure of the extracellular solute binding protein, YejA, has been determined, revealing an oligopeptide-binding protein fold enclosing a ligand-binding pocket larger than those of other peptide-binding proteins of known structure. Prominent electron density in this cavity defines an undecapeptide sequence LGEPRYAFNFN, an observation that is confirmed by mass spectrometry. In the structure, the peptide interactions with the protein are mediated by main chain hydrogen bonds with the exception of Arg5 whose guanidinium side chain makes a set of defining polar interactions with four YejA residues. More detailed characterization of purified recombinant YejA, by a combination of ESI and MALDI-mass spectrometry as well as thermal shift assays, reveals a set of YejA complexes containing overlapping peptides 10-19 residues in length. All contain the sequence LGEPRYAFN. Curiously, these peptides correspond to residues 8-26 of the mature YejA protein, which belong to a unique N-terminal extension that distinguishes YejA from other cluster C oligopeptide binding proteins of known structure. This 35-residue extension is well-ordered and packs across the surface of the protein. The undecapeptide ligand occupies only a fraction of the enclosed pocket volume suggesting the possibility that much larger peptides or peptide conjugates could be accommodated, though thermal shift assays of YejA binding to antimicrobial peptides and peptides unrelated to LGEPRYAFNFN have not provided evidence of binding. While the physiological significance of this 'auto-binding' is not clear, the experimental data suggest that it is not an artefact of the crystallization process and that it may have a function in the sensing of periplasmic or membrane stress.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10924461/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139708383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predatory bacteria prevent the proliferation of intraocular <i>Serratia marcescens</i> and fluoroquinolone-resistant <i>Pseudomonas aeruginosa</i>.","authors":"Eric G Romanowski, Kimberly M Brothers, Rachel C Calvario, Nicholas A Stella, Tami Kim, Mennat Elsayed, Daniel E Kadouri, Robert M Q Shanks","doi":"10.1099/mic.0.001433","DOIUrl":"10.1099/mic.0.001433","url":null,"abstract":"<p><p>Endogenous endophthalmitis caused by Gram-negative bacteria is an intra-ocular infection that can rapidly progress to irreversible loss of vision. While most endophthalmitis isolates are susceptible to antibiotic therapy, the emergence of resistant bacteria necessitates alternative approaches to combat intraocular bacterial proliferation. In this study the ability of predatory bacteria to limit intraocular growth of <i>Pseudomonas aeruginosa</i>, <i>Serratia marcescens</i>, and <i>Staphylococcus aureus</i> was evaluated in a New Zealand white rabbit endophthalmitis prevention model. Predatory bacteria <i>Bdellovibrio bacteriovorus</i> and <i>Micavibrio aeruginosavorus</i> were able to reduce proliferation of keratitis isolates of <i>P. aeruginosa</i> and to a lesser extent <i>S. marcescens</i>. However, it was not able to significantly reduce the number of intraocular <i>S. aureus,</i> which is not a productive prey for these predatory bacteria, suggesting that the inhibitory effect on <i>P. aeruginosa</i> and <i>S. marcescens</i> requires active predation rather than an antimicrobial immune response. Similarly, UV-inactivated <i>B. bacteriovorus</i> were unable to prevent proliferation of <i>P. aeruginosa</i>. Together, these data indicate <i>in vivo</i> inhibition of Gram-negative bacteria proliferation within the intra-ocular environment by predatory bacteria.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10924457/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139736556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}