Journal of Bacteriology最新文献

{"title":"Calprotectin elicits aberrant iron starvation responses in <i>Pseudomonas aeruginosa</i> under anaerobic conditions.","authors":"Jacob M Weiner, Wei Hao Lee, Elizabeth M Nolan, Amanda G Oglesby","doi":"10.1128/jb.00029-25","DOIUrl":"10.1128/jb.00029-25","url":null,"abstract":"<p><p><i>Pseudomonas aeruginosa</i> is an opportunistic pathogen that uses several mechanisms to survive in the iron-limiting host environment. The innate immune protein calprotectin (CP) sequesters ferrous iron [Fe(II)], among other divalent transition metal ions, to limit its availability to pathogens. CP levels are increased in individuals with cystic fibrosis (CF), a hereditary disease that leads to chronic pulmonary infection by <i>P. aeruginosa</i>. We previously showed that aerobic CP treatment of <i>P. aeruginosa</i> induces a multi-metal starvation response that alters expression of several virulence properties. However, the CF lung is a hypoxic environment due to the growth of <i>P. aeruginosa</i> in dense biofilms. Here, we report that anaerobic CP treatment of <i>P. aeruginosa</i> induces many processes associated with an aerobic iron starvation response, including decreased phenazine production and increased expression of the PrrF small regulatory RNAs (sRNAs). However, the iron starvation response elicited by CP in anaerobic conditions shows characteristics that are distinct from responses observed in aerobic growth, including a lack of siderophore production and increased induction of genes for the FeoAB Fe(II) and Phu heme uptake systems. Also distinct from aerobic conditions, CP treatment induces expression of genes for predicted manganese transporters MntH1 and MntH2 during anaerobic growth while eliciting a less robust zinc starvation response compared to aerobic conditions. Induction of <i>mntH2</i> is dependent on the PrrF sRNAs, suggesting a novel example of metal regulatory cross-talk. Thus, anaerobic CP treatment results in a multi-metal starvation response with key distinctions from aerobic conditions, revealing differences in <i>P. aeruginosa</i> metal homeostasis during anaerobic growth.IMPORTANCEIron is critical for most microbial pathogens, and the innate immune system sequesters this metal to limit microbial growth. Pathogens must overcome iron sequestration to survive during infection. For many pathogens, iron homeostasis has primarily been studied in aerobic conditions. Nevertheless, some host environments are hypoxic, including chronic lung infection sites in individuals with cystic fibrosis (CF). Here, we use the innate immune protein calprotectin, which sequesters divalent metal ions including Fe(II), to study the anaerobic iron starvation response of a common CF lung pathogen, <i>Pseudomonas aeruginosa</i>. We report several distinctions of this response during anaerobiosis, highlighting the importance of carefully considering the host environment when investigating the role of nutritional immunity in host-pathogen interactions.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0002925"},"PeriodicalIF":2.7,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12004955/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143709632","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":"A SecA-associated protease modulates the extent of surface display of staphylococcal protein A.","authors":"Muhammad S Azam, Amany M Ibrahim, Owen Leddy, So-Young Oh, Olaf Schneewind, Dominique Missiakas","doi":"10.1128/jb.00522-24","DOIUrl":"10.1128/jb.00522-24","url":null,"abstract":"<p><p>In bacteria, signal peptides direct pre-proteins to the SecYEG secretion channel and are typically cleaved by signal peptidases during translocation across the membrane. In gram-positive bacteria, such as <i>Staphylococcus aureus</i>, some signal peptides have a pre-translocation function. Staphylococcal protein A (SpA) carries such an atypical signal sequence, with a YSIRK/GXXS motif that directs its precursor into the cross-wall of dividing cells for subsequent anchoring by sortase A. Here, we report that PepV-a member of the M20 peptidase family which has been described as a manganese-dependent dipeptidase <i>in vitro</i>-may influence the surface display of precursors with a YSIRK/GXXS motif. SpA deposition into cross-walls was increased in Δ<i>pepV</i> bacteria. Yet, in the absence of <i>pepV</i>, neither the kinetics of signal sequence processing nor the final product of the sorting reaction was altered. In pull-down experiments, PepV was identified as a ligand of SecA. When purified PepV was incubated with SpA precursors, this interaction triggered self-cleavage of the enzyme, an unexpected activity exacerbated by the presence of a chelating agent. In agreement with this finding, a pulse-chase experiment revealed that the half-life of PepV is extended in bacteria lacking <i>spa</i>. Collectively, these data reveal a mutually inhibitory relationship between SpA precursors and PepV, the net result suggesting that while PepV may reduce the surface display of SpA, SpA precursors destabilize PepV possibly to overcome such inhibition.</p><p><strong>Importance: </strong>The \"signal hypothesis\" proposed that N-terminal sequences of secretory proteins contain targeting cues directing nascent polypeptides to the endoplasmic reticulum. This concept was later confirmed as broadly applicable, even to prokaryotes with a single membrane. In gram-positive bacteria, signal sequences bearing the YSIRK/GXXS motif are necessary and sufficient to direct precursors to septal membranes. However, trans-acting factors involved in this spatially restricted targeting remain largely unknown. Here, we identify a member of the M20 metalloprotease family as a potential contributor to the septal surface display of proteins containing YSIRK/GXXS signal peptides.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0052224"},"PeriodicalIF":2.7,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12004944/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143709677","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":"Metabolic characterization of alkane monooxygenases and the growth phenotypes of <i>Pseudomonas aeruginosa</i> ATCC 33988 on hydrocarbons.","authors":"Thusitha S Gunasekera, Loryn L Bowen, Jhoanna C Alger","doi":"10.1128/jb.00508-24","DOIUrl":"10.1128/jb.00508-24","url":null,"abstract":"<p><p>There is a demand and widespread interest in evaluating microbial community structures and metabolic processes in hydrocarbon environments. The current work aims to detect microbial subgroups (phenotypic subsets) and their metabolic processes, such as substrate specificity and expression of niche-associated genes. In this study, we were able to discriminate different cell types in real time from a complex sample matrix to allow the detection of live, dead, and injured cell populations in jet fuels. We found that the expression of <i>alkB1</i> and <i>alkB2</i> genes is induced in a growth-dependent manner and <i>alkB2</i> induction started before <i>alkB1</i>. This indicates that as an early response of <i>Pseudomonas aeruginosa</i> cells' exposure to alkanes, cells activate <i>alkB2</i> gene induction. Deletion of <i>alkB1</i> and <i>alkB2</i> genes completely inhibited <i>P. aeruginosa</i> ATCC 33988 growth in jet fuel, suggesting that two alkane monooxygenases are responsible for the degradation of alkanes and jet fuel. Interestingly, the AlkB2 has a broader (<i>n</i>-C8<i>-n</i>-C16) substrate range compared to AlkB1 (<i>n</i>-C12-<i>n</i>-C16). The data indicate that two alkane utilization pathways can coexist in <i>P. aeruginosa</i> ATCC 33988, and they are differentially expressed in response to <i>n</i>-C6<i>-n-</i>C16 alkanes found in jet fuel. This study provided additional information on the heterogeneity and phenotypic diversity within the same species after exposure to hydrocarbons. This work advances our understanding of microbial community structures and provides new insight into the alkane metabolism of <i>P. aeruginosa</i>.IMPORTANCEAlkane degradation allows for the natural breakdown of hydrocarbons found in crude oil, which can significantly contribute to environmental remediation. The metabolic process of microbes to hydrocarbons and the expression of niche-associated genes are not well understood. <i>Pseudomonas aeruginosa</i> ATCC 33988, originally isolated from a jet fuel tank, degrades hydrocarbons effectively and outcompetes the type strain <i>Pseudomonas aeruginosa</i> PAO1. In this study, we found differential expression of <i>alkB1</i> and <i>alkB2</i> alkane monooxygenase genes and the relative importance of these genes in alkane degradation. We found different phenotypic subsets within the same genotype, which are influenced by hydrocarbon stress. Overall, the research conducted in this study significantly contributes to our knowledge about microbial processes and community structure in hydrocarbon environments.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0050824"},"PeriodicalIF":2.7,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12004949/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143604863","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":"Recent insights into Wzy polymerases and lipopolysaccharide O-antigen biosynthesis.","authors":"Alice Ascari, Renato Morona","doi":"10.1128/jb.00417-24","DOIUrl":"10.1128/jb.00417-24","url":null,"abstract":"<p><p>Bacteria synthesize a plethora of complex surface-associated polysaccharides which enable them to persist and thrive in distinct niches. These glycans serve an array of purposes pertaining to virulence, colonization, antimicrobial resistance, stealth, and biofilm formation. The Wzx/Wzy-dependent pathway is universally the predominant system for bacterial polysaccharide synthesis. This system is responsible for the production of lipopolysaccharide (LPS) O-antigen (Oag), enterobacterial common antigen, capsule, and exopolysaccharides, with orthologs present in both Gram-negative and Gram-positive microbes. Studies focusing principally on <i>Pseudomonas</i>, <i>Shigella</i>, and <i>Salmonella</i> LPS Oag synthesis have provided much of the framework underpinning the biochemical and molecular mechanism behind polysaccharide synthesis via this pathway. LPS Oag production via the Wzx/Wzy-dependent pathway occurs through the stepwise activity of multiple key biosynthetic enzymes, including primarily the polymerase, Wzy, which is responsible for the Oag assembly, and the polysaccharide co-polymerase, Wzz, which effectively modulates the length of the glycan produced. In this review, we provide a comprehensive summary of the latest genetic, structural, and mechanistic data for the main protein candidates of the Wzx/Wzy-dependent pathway, in addition to an examination of their substrate specificities. Furthermore, we have reviewed recent insights pertaining to the dynamics/kinetics of glycan synthesis by this mechanism, including the interplay of the key proteins among themselves and in complex with their substrate. Lastly, we outline key gaps in the literature and suggest future research avenues, with the aim to stimulate ongoing research into this critical pathway responsible for the production of key virulence factors for numerous debilitating and lethal pathogens.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0041724"},"PeriodicalIF":2.7,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12004945/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143604869","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":"Role of a TonB-dependent receptor and an oxygenase in iron-dependent copper resistance in <i>Caulobacter crescentus</i>.","authors":"Pauline Cherry, Hala Kasmo, Mauro Godelaine, Françoise Tilquin, Marc Dieu, Patsy Renard, Jean-Yves Matroule","doi":"10.1128/jb.00493-24","DOIUrl":"10.1128/jb.00493-24","url":null,"abstract":"<p><p>Copper (Cu) is potentially threatening for living organisms owing to its toxicity at high concentrations, requiring the onset of diverse detoxification strategies to maintain fitness. We previously showed that the environmental conditions modulate the response of the oligotrophic alphaproteobacterium <i>Caulobacter crescentus</i> to Cu excess. In the present study, we investigated the role of the Fe-importing TonB-dependent receptor (TBDR) CciT and its partner, CciO, a 2-oxoglutarate/Fe²⁺-dependent oxygenase, in Cu resistance. CciT is specifically involved in Cu resistance in both rich and poor media. Using inductively coupled plasma optical emission spectrometry, we found that under Cu stress, the cellular Cu content is reduced by overexpression of <i>cciT</i>, while the Fe content increases. Mutations of the three known Fe-importing TBDRs reveal that CciT is the primary Fe importer in these conditions and the only TBDR required for Cu resistance. In addition, the extracellular Fe concentration is positively correlated with the cellular Fe content and negatively correlated with the cellular Cu content, resulting in the protection of the cells against Cu excess. The operon organization of <i>cciT</i> and <i>cciO</i> is highly conserved across bacteria, indicating a functional link between the two proteins. Deletion of <i>cciT</i>, <i>cciO</i>, or both genes leads to similar Cu sensitivity. Catalytic mutations in CciT and CciO also result in Cu sensitivity. While CciO is not required for Cu and Fe transport, its precise function remains unknown. Overall, this study provides new insights into the role of Fe uptake in Cu resistance, emphasizing the critical influence of environmental conditions on bacterial physiology.IMPORTANCECopper is an essential metal for many living organisms, as it helps to drive crucial chemical reactions. However, when present in excess, copper turns toxic due to its high reactivity with biological molecules. Bacteria may encounter excess copper in various environments, such as polluted soils, agricultural copper treatments, and within the vacuoles of infected macrophages. In this study, we investigated the copper response in the environmental bacterium <i>Caulobacter crescentus</i>. Our findings reveal that environmental iron levels play a critical role in copper resistance, as increased iron prevents cellular copper accumulation and toxicity. We identified two essential proteins, CciT and CciO, that are involved in iron transport, providing protection against copper excess.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0049324"},"PeriodicalIF":2.7,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12004943/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143624851","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>Mycobacterium tuberculosis</i> FtsB and PerM interact via a C-terminal helix in FtsB to modulate cell division.","authors":"João Ramalheira Ferreira, Ruilan Xu, Zach Hensel","doi":"10.1128/jb.00444-24","DOIUrl":"10.1128/jb.00444-24","url":null,"abstract":"<p><p>Latent infection by <i>Mycobacterium tuberculosis</i> (Mtb) impedes effective tuberculosis therapy and eradication. The protein PerM is essential for chronic Mtb infections in mice and acts via the divisome protein FtsB to modulate cell division. Using transgenic co-expression in <i>Escherichia coli</i>, we studied the Mtb PerM-FtsB interaction in isolation from other Mtb proteins, engineering PerM to enhance expression in the <i>E. coli</i> membrane. Using fluorescence microscopy in <i>E. coli</i>, we observed that the previously reported PerM-dependent instability of Mtb FtsB required a segment of FtsB predicted to bind cell-division proteins FtsL and FtsQ. Furthermore, we found that the stability of membrane-localized PerM hinged on its interaction with a conserved, C-terminal helix in FtsB. We also observed that removing this helix disrupted PerM-FtsB interaction using single-molecule tracking. Molecular dynamics results supported the observation that FtsB stabilized PerM and suggested that interactions at the PerM-FtsB interface differ from our initial structure prediction in a way that is consistent with PerM sequence conservation. Although narrowly conserved, the PerM-FtsB interaction emerges as a potential therapeutic target for persistent infections by disrupting the regulation of cell division. Integrating protein structure prediction, molecular dynamics, and single-molecule microscopy, our approach is primed to screen potential inhibitors of the PerM-FtsB interaction and can be straightforwardly adapted to explore other putative interactions.IMPORTANCEOur research reveals significant insights into the dynamic interaction between the proteins PerM and FtsB within <i>Mycobacterium tuberculosis</i>, contributing to our understanding of bacterial cell division mechanisms crucial for infection persistence. By combining innovative fluorescence microscopy and molecular dynamics, we established that the stability of these proteins is interdependent; molecular dynamics placing PerM-FtsB in the context of the mycobacterial divisome shows how disrupting PerM-FtsB interactions can plausibly impact bacterial cell wall synthesis. These findings highlight the PerM-FtsB interface as a promising target for novel therapeutics aimed at combating persistent bacterial infections. Importantly, our approach can be adapted for similar studies in other bacterial systems, suggesting broad implications for microbial biology and antibiotic development.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0044424"},"PeriodicalIF":2.7,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12004960/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143709660","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":"PqsE adapts the activity of the <i>Pseudomonas aeruginosa</i> quorum-sensing transcription factor RhlR to both autoinducer concentration and promoter sequence identity.","authors":"Bilalay V Tchadi, Jesse J Derringer, Anna K Detweiler, Isabelle R Taylor","doi":"10.1128/jb.00516-24","DOIUrl":"https://doi.org/10.1128/jb.00516-24","url":null,"abstract":"<p><p><i>Pseudomonas aeruginosa</i> is an opportunistic human pathogen that poses a significant health threat. Many pathogenic behaviors of <i>P. aeruginosa</i> are under control of the bacterial cell-cell communication system known as quorum sensing (QS). One of the QS master regulators, RhlR, is a receptor/transcription factor that not only relies on binding of its canonical ligand, <i>N</i>-butyrylhomoserine lactone (C4-HSL), but additionally requires a protein-protein interaction with the enzyme, PqsE. We constructed heterologous reporter strains in <i>Escherichia coli</i> that allow measurements of the reliance of RhlR on C4-HSL and/or PqsE binding for the ability to activate transcription of three RhlR-regulated genes: <i>rhlA</i> (PqsE independent), <i>phzM</i> (PqsE dependent), and <i>azeB</i> (PqsE inhibited). Analogous assays measuring activation of the three genes in <i>P. aeruginosa</i> were performed, and the patterns observed correlated tightly with the heterologous reporter assays. These results confirm that the binding of PqsE to RhlR is able to fine-tune RhlR transcription factor activity in a promoter-specific manner and prove that this ability is independent of other factors present in <i>P. aeruginosa</i>.IMPORTANCE<i>Pseudomonas aeruginosa</i> is an opportunistic human pathogen that can cause fatal infections. There exists an urgent need for new, effective antimicrobial agents to combat <i>P. aeruginosa</i>. The PqsE-RhlR protein-protein interaction is essential for <i>P. aeruginosa</i> to be able to make toxins, form biofilms, and infect host organisms. In this study, we use both non-native models in <i>Escherichia coli</i> and measurements of gene expression/toxin production in <i>P. aeruginosa</i> to show that the PqsE-RhlR interaction enables fine-tuned gene expression and a heightened ability of <i>P. aeruginosa</i> to adapt to external conditions. These findings will be highly valuable as continued efforts are made to design inhibitors of the PqsE-RhlR interaction and test them as potential antimicrobial agents against <i>P. aeruginosa</i> infections.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0051624"},"PeriodicalIF":2.7,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143968459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interplay of virulence factors and signaling molecules: albumin and calcium-mediated biofilm regulation in <i>Bordetella bronchiseptica</i>.","authors":"Sabrina Laura Mugni, Nicolás Ambrosis, George A O Toole, Federico Sisti, Julieta Fernández","doi":"10.1128/jb.00445-24","DOIUrl":"10.1128/jb.00445-24","url":null,"abstract":"<p><p><i>Bordetella bronchiseptica,</i> a respiratory pathogen capable of infecting various mammals, including humans, is associated with chronic infections. <i>B. bronchiseptica</i> can form biofilm-like structures <i>in vivo</i>, providing tolerance against environmental stresses. Recent studies have highlighted the role of cyclic diguanylate monophosphate (c-di-GMP) in this process <i>in vitro</i>: elevated c-di-GMP levels stimulate biofilm formation, whereas phosphodiesterase (PDE) activation reduces biofilms. Respiratory secretions, which contain albumin and calcium at higher concentrations than standard growth media, promote an increase in the amount and extracellular localization of the adenylate cyclase toxin (ACT), an important virulence factor of <i>Bordetella spp</i>. Secreted ACT, present in the extracellular medium or attached to the outer membrane, inhibits biofilm formation. Based on these observations, we hypothesized that serum albumin and calcium together inhibit biofilm formation and explored the potential role of c-di-GMP in this process. Our findings suggest that serum albumin and calcium inhibit <i>B. bronchiseptica</i> biofilm formation through two potentially independent mechanisms: one involving ACT secretion and another promoting c-di-GMP degradation. In the presence of albumin and calcium, intracellular levels of c-di-GMP were reduced, and specific PDEs appear to be involved in this process. In addition, albumin and calcium stimulated the secretion of the adhesin BrtA. This study contributes to the understanding of the mechanisms governing <i>B. bronchiseptica</i> biofilm formation and its modulation by host factors.IMPORTANCE<i>Bordetella bronchiseptica</i>, a respiratory pathogen capable of infecting various mammals, forms biofilms that enhance its ability to withstand environmental stresses. This study reveals that host-derived factors, specifically serum albumin and calcium, inhibit biofilm formation through two independent mechanisms: increasing adenylate cyclase toxin secretion and promoting the degradation of cyclic diguanylate monophosphate (c-di-GMP), a key biofilm regulator. These findings provide insights into how host conditions influence <i>B. bronchiseptica</i> biofilm dynamics, shedding light on the complex interactions between pathogen and host that contribute to infection persistence. Understanding these mechanisms may inform strategies to mitigate chronic infections caused by <i>B. bronchiseptica</i>.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0044524"},"PeriodicalIF":2.7,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12004968/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143709845","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":"A co-conserved gene pair supports <i>Caulobacter</i> iron homeostasis during chelation stress.","authors":"Sergio Hernandez-Ortiz, Kiwon Ok, Thomas V O'Halloran, Aretha Fiebig, Sean Crosson","doi":"10.1128/jb.00484-24","DOIUrl":"10.1128/jb.00484-24","url":null,"abstract":"<p><p>Synthetic metal chelators are widely used in industrial, clinical, and agricultural settings, leading to their accumulation in the environment. We measured the growth of <i>Caulobacter crescentus</i>, a soil and aquatic bacterium, in the presence of the ubiquitous chelator ethylenediaminetetraacetic acid (EDTA) and found that it restricts growth by lowering intracellular iron levels. Using barcoded transposon sequencing, we identified an operonic gene pair, <i>cciT-cciO</i>, that is required to maintain iron homeostasis in laboratory media during EDTA challenge. <i>cciT</i> encodes one of four TonB-dependent transporters that are regulated by the ferric uptake repressor (Fur) and stands out among this group of genes in its ability to support <i>Caulobacter</i> growth across diverse media conditions. The function of CciT strictly requires <i>cciO</i>, which encodes a cytoplasmic Fe^II dioxygenase-family protein. Our results thus define a functional partnership between an outer membrane iron receptor and a cytoplasmic dioxygenase that are broadly co-conserved in Proteobacteria. We expanded our analysis to natural environments by examining the growth of mutant strains in freshwater from two lakes, each with biochemical and geochemical profiles that differ markedly from standard laboratory media. In lake water, <i>Caulobacter</i> growth did not require <i>cciT</i> or <i>cciO</i> and was less affected by EDTA treatment. This result aligns with our observation that EDTA toxicity is influenced by common forms of biologically chelated iron and the spectrum of free cations present in the medium. Our study defines a conserved iron acquisition system in Proteobacteria and bridges laboratory-based physiology studies with real-world conditions.IMPORTANCEMetal-chelating chemicals are widely used across industries, including as preservatives in the food sector, but their full impact on microbial physiology is not well understood. We identified two genes, <i>cciT</i> and <i>cciO</i>, that function together to support <i>Caulobacter crescentus</i> iron balance when cells are exposed to the common synthetic chelator, EDTA. CciT is an outer membrane transporter and CciO is a dioxygenase-family protein that are mutually conserved in many bacteria, including human pathogens where mutations in <i>cciT</i> homologs are linked to clinical resistance to the siderophore antibiotic cefiderocol. This study identifies a conserved genetic system that supports iron homeostasis during chelation stress and illuminates the iron acquisition versatility and stress resilience of <i>Caulobacter</i> in freshwater environments.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0048424"},"PeriodicalIF":2.7,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12004947/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143624846","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":"A call for healing and unity.","authors":"Patrick D Schloss","doi":"10.1128/jb.00067-25","DOIUrl":"10.1128/jb.00067-25","url":null,"abstract":"","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0006725"},"PeriodicalIF":2.7,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12004939/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143515564","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}