Journal of Bacteriology最新文献

{"title":"Identification and characterization of the <i>Bacillus subtilis</i> spore germination protein GerY.","authors":"Fernando H Ramírez-Guadiana, Anna P Brogan, David Z Rudner","doi":"10.1128/jb.00399-24","DOIUrl":"10.1128/jb.00399-24","url":null,"abstract":"<p><p>In response to starvation, endospore-forming bacteria differentiate into stress-resistant spores that can remain dormant for years yet rapidly germinate and resume growth when nutrients become available. To identify uncharacterized factors involved in the exit from dormancy, we performed a transposon-sequencing screen taking advantage of the loss of spore heat resistance that accompanies germination. We reasoned that transposon insertions that impair but do not block germination will lose resistance more slowly than wild type after exposure to nutrients and will therefore survive heat treatment. Using this approach, we identified most of the known germination genes and several new ones. We report an initial characterization of 15 of these genes and a more detailed analysis of one (<i>ymaF</i>). Spores lacking <i>ymaF</i> (renamed <i>gerY</i>) are impaired in germination in response to both L-alanine and L-asparagine, D-glucose, D-fructose, and K⁺. GerY is a soluble protein synthesized under <i>σ</i>^<i>E</i> control in the mother cell. A YFP-GerY fusion localizes around the developing and mature spore in a manner that depends on CotE and SafA, indicating that it is a component of the spore coat. Coat proteins encoded by the <i>gerP</i> operon and <i>gerT</i> are also required for efficient germination, and we show that spores lacking two or all three of these loci have more severe defects in the exit from dormancy. Our data are consistent with a model in which GerY, GerT, and the GerP proteins are required for efficient transit of nutrients through the coat to access the germination receptors, but each acts independently in this process.</p><p><strong>Importance: </strong>Pathogens in the orders Bacillales and Clostridiales resist sterilization by differentiating into stress-resistant spores. Spores are metabolically inactive and can remain dormant for decades, yet upon exposure to nutrients, they rapidly resume growth, causing food spoilage, food-borne illness, or life-threatening disease. The exit from dormancy, called germination, is a key target in combating these important pathogens. Here, we report a high-throughput genetic screen using transposon sequencing to identify novel germination factors that ensure the efficient exit from dormancy. We identify several new factors and characterize one in greater detail. This factor, renamed GerY, is part of the proteinaceous coat that encapsulates the dormant spore. Our data suggest that GerY enables efficient transit of nutrients through the coat to trigger germination.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0039924"},"PeriodicalIF":2.7,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11656775/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142621089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Legionella pneumophila</i>, a Rosetta stone to understanding bacterial pathogenesis.","authors":"Katerina A Romanov, Tamara J O'Connor","doi":"10.1128/jb.00324-24","DOIUrl":"10.1128/jb.00324-24","url":null,"abstract":"<p><p><i>Legionella pneumophila</i> is an environmentally acquired pathogen that causes respiratory disease in humans. While the discovery of <i>L. pneumophila</i> is relatively recent compared to other bacterial pathogens, over the past 50 years, <i>L. pneumophila</i> has emerged as a powerhouse for studying host-pathogen interactions. In its natural habitat of fresh water, <i>L. pneumophila</i> interacts with a diverse array of protozoan hosts and readily evolve to expand their host range. This has led to the accumulation of the most extensive arsenal of secreted virulence factors described for a bacterial pathogen and their ability to infect humans. Within amoebae and human alveolar macrophages, the bacteria replicate within specialized membrane-bound compartments, establishing <i>L. pneumophila</i> as a model for studying intracellular vacuolar pathogens. In contrast, the virulence factors required for intracellular replication are specifically tailored to individual host cells types, allowing the pathogen to adapt to variation between disparate niches. The broad host range of this pathogen, combined with the extensive diversity and genome plasticity across the <i>Legionella</i> genus, has thus established this bacterium as an archetype to interrogate pathogen evolution, functional genomics, and ecology. In this review, we highlight the features of <i>Legionella</i> that establish them as a versatile model organism, new paradigms in bacteriology and bacterial pathogenesis resulting from the study of <i>Legionella</i>, as well as current and future questions that will undoubtedly expand our understanding of the complex and intricate biology of the microbial world.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0032424"},"PeriodicalIF":2.7,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11656745/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142785699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MoaB2, a newly identified transcription factor, binds to σ^A in <i>Mycobacterium smegmatis</i>.","authors":"Barbora Brezovská, Subhash Narasimhan, Michaela Šiková, Hana Šanderová, Tomáš Kovaľ, Nabajyoti Borah, Mahmoud Shoman, Debora Pospíšilová, Viola Vaňková Hausnerová, Dávid Tužinčin, Martin Černý, Jan Komárek, Martina Janoušková, Milada Kambová, Petr Halada, Alena Křenková, Martin Hubálek, Mária Trundová, Jan Dohnálek, Jarmila Hnilicová, Lukáš Žídek, Libor Krásný","doi":"10.1128/jb.00066-24","DOIUrl":"10.1128/jb.00066-24","url":null,"abstract":"<p><p>In mycobacteria, σ^A is the primary sigma factor. This essential protein binds to RNA polymerase (RNAP) and mediates transcription initiation of housekeeping genes. Our knowledge about this factor in mycobacteria is limited. Here, we performed an unbiased search for interacting partners of <i>Mycobacterium smegmatis</i> σ^A. The search revealed a number of proteins; prominent among them was MoaB2. The σ^A-MoaB2 interaction was validated and characterized by several approaches, revealing that it likely does not require RNAP and is specific, as alternative σ factors (<i>e.g.</i>, closely related σ^B) do not interact with MoaB2. The structure of MoaB2 was solved by X-ray crystallography. By immunoprecipitation and nuclear magnetic resonance, the unique, unstructured N-terminal domain of σ^A was identified to play a role in the σ^A-MoaB2 interaction. Functional experiments then showed that MoaB2 inhibits σ^A-dependent (but not σ^B-dependent) transcription and may increase the stability of σ^A in the cell. We propose that MoaB2, by sequestering σ^A, has a potential to modulate gene expression. In summary, this study has uncovered a new binding partner of mycobacterial σ^A, paving the way for future investigation of this phenomenon.IMPORTANCEMycobacteria cause serious human diseases such as tuberculosis and leprosy. The mycobacterial transcription machinery is unique, containing transcription factors such as RbpA, CarD, and the RNA polymerase (RNAP) core-interacting small RNA Ms1. Here, we extend our knowledge of the mycobacterial transcription apparatus by identifying MoaB2 as an interacting partner of σ^A, the primary sigma factor, and characterize its effects on transcription and σ^A stability. This information expands our knowledge of interacting partners of subunits of mycobacterial RNAP, providing opportunities for future development of antimycobacterial compounds.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0006624"},"PeriodicalIF":2.7,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11656743/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142583303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quorum sensing regulation of Psl polysaccharide production by <i>Pseudomonas aeruginosa</i>.","authors":"Jeffrey N Carey, Sabrina Lamont, Daniel J Wozniak, Ajai A Dandekar, Matthew R Parsek","doi":"10.1128/jb.00312-24","DOIUrl":"10.1128/jb.00312-24","url":null,"abstract":"<p><p><i>Pseudomonas aeruginosa</i> is a common opportunistic pathogen and a model organism for studying bacterial sociality. A social behavior of <i>P. aeruginosa</i> that is critical for its success as a pathogen is its ability to form protective biofilms. Many of <i>P. aeruginosa</i>'s social phenotypes are regulated by quorum sensing-a type of cell-cell communication that allows bacteria to respond to population density. Although biofilm formation is known to be affected by quorum sensing, evidence for direct regulation of biofilm production by quorum regulators has remained elusive. In this work, we show that production of the major biofilm matrix polysaccharide Psl in <i>P. aeruginosa</i> PAO1 is regulated by the quorum regulators LasR and RhlR in stationary-phase cultures. Secretion of Psl into the culture medium requires LasR, RhlR, and the quorum signal molecules <i>N</i>-3-oxo-dodecanoyl-homoserine lactone and <i>N</i>-butanoyl homoserine lactone. Psl production in strains unable to synthesize the homoserine lactone signals can be restored by exogenous introduction of the signal molecules. We found that LasR and RhlR perform different roles in the regulation of Psl production: LasR acts at the promoter of the <i>psl</i> operon and activates transcription of the Psl biosynthetic genes, while RhlR activates translation of the <i>psl</i> transcripts. This work contributes to our understanding of the overlapping but distinct functions of the Las and Rhl quorum-sensing systems and implicates both in the direct regulation of biofilm matrix production.IMPORTANCE<i>Pseudomonas aeruginosa</i> biofilms are responsible for many treatment-resistant infections in humans. Many cooperative behaviors in <i>P. aeruginosa</i> are controlled by quorum sensing, but evidence for a direct role of quorum sensing in the regulation of biofilm matrix production has been scant. In this work, we show that the Las and Rhl quorum-sensing systems have distinct roles in regulating production of the matrix polysaccharide Psl and that this regulation happens at the level of transcription (Las) and translation (Rhl) of the <i>psl</i> operon. These findings deepen our understanding of overlapping functions of Las and Rhl quorum sensing and the complex regulation of biofilm development in <i>P. aeruginosa</i>.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0031224"},"PeriodicalIF":2.7,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11656772/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142621091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Increasing prevalence of bacteriocin carriage in a 6-year hospital cohort of <i>E. faecium</i>.","authors":"Andrea Garretto, Suzanne Dawid, Robert Woods","doi":"10.1128/jb.00294-24","DOIUrl":"10.1128/jb.00294-24","url":null,"abstract":"<p><p>Vancomycin-resistant enterococci (VRE) are important pathogens in hospitalized patients; however, the factors involved in VRE colonization of hospitalized patients are not well characterized. Bacteriocins provide a competitive advantage to enterococci in experimental models of colonization, but little is known about bacteriocin content in samples derived from humans and even less is known about their dynamics in the clinical setting. To identify bacteriocins which may be relevant in the transmission of VRE, we present a systematic analysis of bacteriocin content in the genomes of 2,248 patient-derived <i>E. faecium</i> isolates collected over a 6-year period from a single hospital system. We used computational methods to broadly search for bacteriocin structural genes and a functional assay to look for phenotypes consistent with bacteriocin expression. We identified homology to 15 different bacteriocins, with 2 having a high presence in this clinical cohort. Bacteriocin 43 (bac43) was found in a total of 58% of isolates, increasing from 8% to 91% presence over the 6-year collection period. There was little genetic variation in the bac43 structural or immunity genes across isolates. The enterocin A structural gene was found in 98% of isolates, but only 0.3% of isolates had an intact enterocin A gene cluster and displayed a bacteriocin-producing phenotype. This study presents a wide survey of bacteriocins from hospital isolates and identified bac43 as highly conserved, increasing in prevalence, and phenotypically functional. This makes bac43 an interesting target for future investigation for a potential role in <i>E. faecium</i> transmission.IMPORTANCEWhile enterococci are a normal inhabitant of the human gut, vancomycin-resistant <i>E. faecalis</i> and <i>E. faecium</i> are urgent public health threats responsible for hospital-associated infections. Bacteriocins are ribosomally synthesized antimicrobial proteins and are commonly used by bacteria to provide a competitive advantage in polymicrobial environments. Bacteriocins have the potential to be used by <i>E. faecium</i> to invade and dominate the human gut leading to a greater propensity for transmission. In this work, we explore bacteriocin content in a defined clinically derived population of <i>E. faecium</i> using both genetic and phenotypic studies. We show that one highly active bacteriocin is increasing in prevalence over time and demonstrates great potential relevance to <i>E. faecium</i> transmission.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0029424"},"PeriodicalIF":2.7,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11656788/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142780289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Architectural dissection of adhesive bacterial cell surface appendages from a \"molecular machines\" viewpoint.","authors":"Olivia E R Smith, Tanmay A M Bharat","doi":"10.1128/jb.00290-24","DOIUrl":"10.1128/jb.00290-24","url":null,"abstract":"<p><p>The ability of bacteria to interact with and respond to their environment is crucial to their lifestyle and survival. Bacterial cells routinely need to engage with extracellular target molecules, in locations spatially separated from their cell surface. Engagement with distant targets allows bacteria to adhere to abiotic surfaces and host cells, sense harmful or friendly molecules in their vicinity, as well as establish symbiotic interactions with neighboring cells in multicellular communities such as biofilms. Binding to extracellular molecules also facilitates transmission of information back to the originating cell, allowing the cell to respond appropriately to external stimuli, which is critical throughout the bacterial life cycle. This requirement of bacteria to bind to spatially separated targets is fulfilled by a myriad of specialized cell surface molecules, which often have an extended, filamentous arrangement. In this review, we compare and contrast such molecules from diverse bacteria, which fulfil a range of binding functions critical for the cell. Our comparison shows that even though these extended molecules have vastly different sequence, biochemical and functional characteristics, they share common architectural principles that underpin bacterial adhesion in a variety of contexts. In this light, we can consider different bacterial adhesins under one umbrella, specifically from the point of view of a modular molecular machine, with each part fulfilling a distinct architectural role. Such a treatise provides an opportunity to discover fundamental molecular principles governing surface sensing, bacterial adhesion, and biofilm formation.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0029024"},"PeriodicalIF":2.7,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7616799/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142583301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The vibriophage-encoded inhibitor OrbA abrogates BREX-mediated defense through the ATPase BrxC.","authors":"Reid T Oshiro, Drew T Dunham, Kimberley D Seed","doi":"10.1128/jb.00206-24","DOIUrl":"10.1128/jb.00206-24","url":null,"abstract":"<p><p>Bacteria and phages are locked in a co-evolutionary arms race where each entity evolves mechanisms to restrict the proliferation of the other. Phage-encoded defense inhibitors have proven powerful tools to interrogate how defense systems function. A relatively common defense system is BREX (bacteriophage exclusion); however, how BREX functions to restrict phage infection remains poorly understood. A BREX system encoded by the <u>s</u>ulfametho<u>x</u>azole and <u>t</u>rimethoprim (SXT) integrative and conjugative element, <i>Vch</i>Ind5, was recently identified in <i>Vibrio cholerae</i>, the causative agent of the diarrheal disease cholera. The lytic phage ICP1 (<u>I</u>nternational Centre for Diarrhoeal Disease Research, Bangladesh <u>c</u>holera <u>p</u>hage <u>1</u>) that co-circulates with <i>V. cholerae</i> encodes the BREX-inhibitor OrbA, but how OrbA inhibits BREX is unclear. Here, we determine that OrbA inhibits BREX using a unique mechanism from known BREX inhibitors by directly binding to the BREX component BrxC. BrxC has a functional ATPase domain that, when mutated, not only disrupts BrxC function but also alters how BrxC multimerizes. Furthermore, we find that OrbA binding disrupts BrxC-BrxC interactions. We determine that OrbA cannot bind BrxC encoded by the distantly related BREX system encoded by the aSXT <i>Vch</i>Ban9, and thus fails to inhibit this BREX system that also circulates in epidemic <i>V. cholerae</i>. Lastly, we find that homologs of the <i>Vch</i>Ind5 BrxC are more diverse than the homologs of the <i>Vch</i>Ban9 BrxC. These data provide new insight into the function of the BrxC ATPase and highlight how phage-encoded inhibitors can disrupt phage defense systems using different mechanisms.IMPORTANCEWith renewed interest in phage therapy to combat antibiotic-resistant pathogens, understanding the mechanisms bacteria use to defend themselves against phages and the counter-strategies phages evolve to inhibit defenses is paramount. Bacteriophage exclusion (BREX) is a common defense system with few known inhibitors. Here, we probe how the vibriophage-encoded inhibitor OrbA inhibits the BREX system of <i>Vibrio cholerae</i>, the causative agent of the diarrheal disease cholera. By interrogating OrbA function, we have begun to understand the importance and function of a BREX component. Our results demonstrate the importance of identifying inhibitors against defense systems, as they are powerful tools for dissecting defense activity and can inform strategies to increase the efficacy of some phage therapies.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0020624"},"PeriodicalIF":2.7,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11580459/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142466183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combinatorial control of type IVa pili formation by the four polarized regulators MglA, SgmX, FrzS, and SopA.","authors":"Michel Oklitschek, Luís António Menezes Carreira, Memduha Muratoğlu, Lotte Søgaard-Andersen, Anke Treuner-Lange","doi":"10.1128/jb.00108-24","DOIUrl":"10.1128/jb.00108-24","url":null,"abstract":"<p><p>Type IVa pili (T4aP) are widespread and enable bacteria to translocate across surfaces. T4aP engage in cycles of extension, surface adhesion, and retraction, thereby pulling cells forward. Accordingly, the number and localization of T4aP are critical to efficient translocation. Here, we address how T4aP formation is regulated in <i>Myxococcus xanthus</i>, which translocates with a well-defined leading and lagging cell pole using T4aP at the leading pole. This localization is orchestrated by the small GTPase MglA and its downstream effector SgmX that both localize at the leading pole and recruit the PilB extension ATPase to the T4aP machinery at this pole. Here, we identify the previously uncharacterized protein SopA and show that it interacts directly with SgmX, localizes at the leading pole, stimulates polar localization of PilB, and is important for T4aP formation. We corroborate that MglA also recruits FrzS to the leading pole, and FrzS stimulates SgmX recruitment. In addition, FrzS and SgmX separately recruit SopA. Precise quantification of T4aP-formation and T4aP-dependent motility in various mutants supports a model whereby the main pathway for stimulating T4aP formation is the MglA/SgmX pathway. FrzS stimulates this pathway by recruiting SgmX and SopA. SopA stimulates the MglA/SgmX pathway by stimulating the function of SgmX, likely by promoting the SgmX-dependent recruitment of PilB to the T4aP machinery. The architecture of the MglA/SgmX/FrzS/SopA protein interaction network for orchestrating T4aP formation allows for combinatorial regulation of T4aP levels at the leading cell pole resulting in discrete levels of T4aP-dependent motility.</p><p><strong>Importance: </strong>Type IVa pili (T4aP) are widespread bacterial cell surface structures with important functions in translocation across surfaces, surface adhesion, biofilm formation, and virulence. T4aP-dependent translocation crucially depends on the number of pili. To address how the number of T4aP is regulated, we focused on <i>M. xanthus</i>, which assembles T4aP at the leading cell pole and is a model organism for T4aP biology. Our results support a model whereby the four proteins MglA, SgmX, FrzS, and the newly identified SopA protein establish a highly intricate interaction network for orchestrating T4aP formation at the leading cell pole. This network allows for combinatorial regulation of the number of T4aP resulting in discrete levels of T4aP-dependent motility.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0010824"},"PeriodicalIF":2.7,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11580455/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142466179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The efflux system CdfX exports zinc that cannot be transported by ZntA in <i>Cupriavidus metallidurans</i>.","authors":"Vladislava Schulz, Diana Galea, Grit Schleuder, Philipp Strohmeyer, Cornelia Große, Martin Herzberg, Dietrich H Nies","doi":"10.1128/jb.00299-24","DOIUrl":"10.1128/jb.00299-24","url":null,"abstract":"<p><p><i>Cupriavidus metallidurans</i> is able to survive exposure to high concentrations of transition metals, but is also able to grow under metal starvation conditions. A prerequisite of cellular zinc homeostasis is a flow equilibrium combining zinc uptake and efflux processes. The mutant strain ∆e4 of the parental plasmid-free strain AE104 with a deletion of all four chromosomally encoded genes of previously known efflux systems ZntA, CadA, DmeF, and FieF was still able to efflux zinc in a pulse-chase experiment, indicating the existence of a fifth efflux system. The gene <i>cdfX</i>, encoding a protein of the cation diffusion facilitator (CDF) family, is located in proximity to the <i>cadA</i> gene, encoding a P-type ATPase. Deletion of <i>cdfX</i> in the ∆e4 mutant resulted in a further decrease in zinc resistance. Pulse-chase experiments with radioactive ⁶⁵Zn(II) and stable-isotope-enriched ⁶⁷Zn(II) provided evidence that CdfX was responsible for the residual zinc efflux activity of the mutant strain ∆e4. Reporter gene fusions with <i>cdfX-lacZ</i> indicated that the MerR-type regulator ZntR, the main regulator of <i>zntA</i> expression, was responsible for zinc- and cadmium-dependent upregulation of <i>cdfX</i> expression, especially in mutant cells lacking one or both of the previously characterized efflux systems, ZntA and CadA. Expression of <i>zntR</i> also proved to be controlled by ZntR itself as well as by zinc and cadmium availability. These data indicate that the <i>cdfX-cadA</i> region provides <i>C. metallidurans</i> with a backup system for the zinc-cadmium-exporting P-type ATPase ZntA, with CdfX exporting zinc and CadA cadmium.IMPORTANCEBacteria have evolved the ability to supply the important trace element zinc to zinc-dependent proteins, despite external zinc concentrations varying over a wide range. Zinc homeostasis can be understood as adaptive layering of homeostatic systems, allowing coverage from extreme starvation to extreme resistance. Central to zinc homeostasis is a flow equilibrium of zinc comprising uptake and efflux reactions, which adjusts the cytoplasmic zinc content. This report describes what happens when an imbalance in zinc and cadmium concentrations impairs the central inner-membrane zinc efflux system for zinc by competitive inhibition for this exporter. The problem is solved by activation of Cd-exporting CadA or Zn-exporting CdfX as additional efflux systems.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0029924"},"PeriodicalIF":2.7,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11580412/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142545640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Vibrio cholerae</i>: a fundamental model system for bacterial genetics and pathogenesis research.","authors":"Julia C van Kessel, Andrew Camilli","doi":"10.1128/jb.00248-24","DOIUrl":"10.1128/jb.00248-24","url":null,"abstract":"<p><p>Species of the <i>Vibrio</i> genus occupy diverse aquatic environments ranging from brackish water to warm equatorial seas to salty coastal regions. More than 80 species of <i>Vibrio</i> have been identified, many of them as pathogens of marine organisms, including fish, shellfish, and corals, causing disease and wreaking havoc on aquacultures and coral reefs. Moreover, many <i>Vibrio</i> species associate with and thrive on chitinous organisms abundant in the ocean. Among the many diverse <i>Vibrio</i> species, the most well-known and studied is <i>Vibrio cholerae</i>, discovered in the 19th century to cause cholera in humans when ingested. The <i>V. cholerae</i> field blossomed in the late 20th century, with studies broadly examining <i>V. cholerae</i> evolution as a human pathogen, natural competence, biofilm formation, and virulence mechanisms, including toxin biology and virulence gene regulation. This review discusses some of the historic discoveries of <i>V. cholerae</i> biology and ecology as one of the fundamental model systems of bacterial genetics and pathogenesis.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0024824"},"PeriodicalIF":2.7,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11580405/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142466177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}