Journal of Bacteriology最新文献

{"title":"From lab reagent to metabolite: the riboswitch ligand guanidine as a relevant compound in bacterial physiology.","authors":"Payton Bowman, Hubert Salvail","doi":"10.1128/jb.00073-25","DOIUrl":"https://doi.org/10.1128/jb.00073-25","url":null,"abstract":"<p><p>Efforts of the last 20 years in validating novel riboswitches led to the identification of numerous new motifs recognizing compounds with well-established biological functions. However, the recent characterization of widespread classes of riboswitches binding the nitrogen-rich compound guanidine raised questions regarding its physiological significance that has so far remained elusive. Recent findings established that certain bacterial species assimilate guanidine as a nitrogen source via guanidine-specific enzymes and transporters and that complete ammonium oxidizers can use it as a sole source of energy, reductant, and nitrogen. The frequent association of guanidine riboswitches with genes encoding guanidine efflux transporters also hints that bacteria may experience the burden of guanidine as a stressor during their lifestyle. A major gap in understanding the biology of guanidine resides in its natural source. While metabolic pathways responsible for guanidine synthesis were defined in plants, only a few guanidine-producing enzymes have been identified in bacteria, despite indications that the model organism <i>E. coli</i> may produce guanidine. This review summarizes how riboswitch research unveiled guanidine as an important compound in living organisms and the recent findings advancing our knowledge of guanidine biology. We also highlight open questions that will orient future research aiming at gaining further insights into the biological relevance of guanidine.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0007325"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144119731","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":"SloR-SRE binding to the <i>S. mutans mntH</i> promoter is cooperative.","authors":"Myrto Ziogas, India Drummond, Igor Todorovic, Katie Kraczkowsky, Yiran Han, Hua Zhang, Hui Wu, Grace Spatafora","doi":"10.1128/jb.00470-24","DOIUrl":"10.1128/jb.00470-24","url":null,"abstract":"<p><p><i>Streptococcus mutans</i> is a commensal member of the plaque microbiome. It is especially prevalent when dietary sugars are available for <i>S. mutans</i> fermentation, generating acid byproducts that lower plaque pH and foster tooth decay. <i>S. mutans</i> can survive in the transient conditions of the mouth, in part because it can regulate the uptake of manganese and iron during periods of feast when metal ions are available, and famine when they are limited. <i>S. mutans</i> depends on a 25kDa metalloregulatory protein, called SloR, to modulate the uptake of these cations across the bacterial cell surface. When bound to manganese, SloR binds to palindromic recognition elements in the promoter of the sloABC genes that encode the major manganese transporter in <i>S. mutans</i>. Reports in the literature describe MntH, an ancillary manganese transporter in <i>S. mutans</i>, that is also subject to SloR control. In the present study, we performed expression profiling experiments that reveal coordinate regulation of the sloABC and mntH genes at the level of transcription. In addition, we describe a role for the mntH gene product that is redundant with that of the sloABC-encoded metal ion uptake machinery. The results of DNA-binding studies support direct SloR binding to the mntH promoter region which, like that at the sloABC promoter, harbors three palindromic recognition elements to which SloR binds cooperatively to repress downstream transcription. These findings expand our understanding of the SloR metalloregulome and elucidate SloR-DNA binding that is essential for <i>S. mutans</i> metal ion homeostasis and fitness in the oral cavity.</p><p><strong>Importance: </strong>Dental caries disproportionately impacts low-income socioeconomic groups in the United States and abroad. Research that is focused on <i>S. mutans</i>, the primary causative agent of dental caries in humans, is significant to mitigation efforts aimed at alleviating or preventing dental caries. The SloR protein is a major regulator of the <i>S. mutans</i> metal ion uptake machinery encoded by the sloABC- and mntH genes. This SloR-mediated gene control is essential for maintaining intracellular metal ion homeostasis, and hence <i>S. mutans</i> fitness in the plaque microbiome. An improved understanding of the sloABC and mntH metal ion transporters and their regulation by SloR can guide rational drug design that, by targeting the SloR-DNA-binding interface, can alleviate or prevent <i>S. mutans</i>-induced disease.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0047024"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12096823/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143752783","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":"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":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12096825/pdf/","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":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The adjacent ATP-binding protein-encoding genes of the <i>Enterococcus faecalis</i> phosphate-specific transport (<i>pst</i>) locus have non-overlapping cellular functions.","authors":"Christopher M Healy, Evelyn A Pham, Keane J Dye, Candace N Rouchon, Biko McMillan, Kristi L Frank","doi":"10.1128/jb.00033-25","DOIUrl":"10.1128/jb.00033-25","url":null,"abstract":"<p><p>The widely conserved <i>pst-phoU</i> operon encodes a low-velocity, high-affinity, ATP-dependent importer for inorganic phosphate (Pi). The <i>pstB</i> gene encodes the ATPase that powers the import of Pi into the cell. In some Firmicutes, including the gastrointestinal commensal and opportunistic pathogen <i>Enterococcus faecalis</i>, the <i>pst-phoU</i> locus contains adjacent <i>pstB</i> genes. In this work, we compared the functionality of <i>E. faecalis pstB1</i> and <i>pstB2. E. faecalis pstB1</i> and <i>pstB2</i> share sequence similarities with verified PstB ATPases from <i>Escherichia coli</i> and <i>Streptococcus pneumoniae</i> and only share ~60% amino acid identity with each other. Deletion of <i>pstB1</i> was associated with a growth defect in low Pi-containing chemically defined medium (CDM), reduced Pi uptake, and a moderate increase in alkaline phosphatase (AP) activity. Deletion of <i>pstB2</i> fully inhibited growth in CDM regardless of inorganic phosphorus source but did not hinder growth in rich, undefined medium. The Δ<i>pstB2</i> mutant also exhibited a significant increase in AP activity that was associated with extracellular Pi accumulation. Overexpression of <i>pstB2</i> in the <i>pstB1</i> mutant was sufficient to restore growth in low-Pi CDM, Pi uptake, and AP activity, but this was not recapitulated with overexpression of <i>pstB1</i> in the Δ<i>pstB2</i> mutant. Deletion of either <i>pstB</i> paralog increased expression of the tandem paralog, and overexpression of <i>pstB2</i> in Δ<i>pstB2</i> reduced <i>pstB1</i> expression. These results suggest that the <i>E. faecalis pstB2</i>-encoded ATPase is required for Pi import, while the <i>pstB1</i>-encoded ATPase has an accessory role in Pi import that can be duplicated by the presence of excess PstB2.</p><p><strong>Importance: </strong>Phosphate is critical for all microbial life. In many bacteria, inorganic phosphate (Pi) is imported by the high-affinity, low-velocity Pst-PhoU system. The <i>pstB</i> gene encodes the ATPase that powers Pi import. The <i>pst-phoU</i> operon in many Firmicutes, including the human commensal and opportunistic pathogen <i>Enterococcus faecalis</i>, contains adjacent <i>pstB</i> genes, <i>pstB1</i> and <i>pstB2</i>. No studies on the relative biological contributions of tandem <i>pstB</i> paralogs in any microbe have been published. This genetic study indicates that <i>E. faecalis pstB1</i> and <i>pstB2</i> do not have equivalent functions. The <i>pstB2</i> gene encodes an ATPase that is required for Pi import, while the ATPase encoded by <i>pstB1</i> has an accessory role in Pi import that can be duplicated by the presence of excess PstB2.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0003325"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12096839/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143985451","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 periplasmic and cytoplasmic faces of septal protein SepJ from filamentous cyanobacteria.","authors":"Enrique Flores","doi":"10.1128/jb.00488-24","DOIUrl":"10.1128/jb.00488-24","url":null,"abstract":"<p><p>Filamentous, N₂-fixing, heterocyst-forming cyanobacteria grow as chains of cells in which intercellular transfer of regulators and metabolites takes place, allowing them to behave as multicellular organisms. Intercellular transfer occurs by diffusion through septal junctions. In the model heterocyst-forming cyanobacterium <i>Anabaena</i> sp. strain PCC 7120, some identified septal proteins, including FraC and FraD, are directly involved in the formation of junctions that have been visualized by cryo-electron tomography, whereas the role of the key septal protein SepJ remains elusive. SepJ can form tetramers and contains coiled-coil, linker, and integral membrane (permease) domains. Using AlphaFold 3, a SepJ tetramer is predicted to have a quaternary structure in which the coiled-coil domain traverses the cytoplasmic membrane through a cavity formed between the four permease domains. Part of the coiled-coil domain is thus located in the septal periplasm, where it can interact with peptidoglycan. This possible SepJ structure can be widespread in filamentous cyanobacteria and explains known properties of SepJ. Structures of SepJ with other septal proteins including SjcF1, SepI, and SepT could also be predicted consistent with their previously described interactions. A possible interaction of the SepJ coiled-coil domain with the catalytic domain of cell wall amidase AmiC1, which would be relevant to prevent filament fragmentation in <i>Anabaena</i>, is also discussed. The renewed view of SepJ presented here offers a molecular basis for understanding the key role of this protein in filament formation and intercellular communication.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0048824"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12096826/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143752787","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":"Antimicrobial peptide plectasin recombinantly produced in <i>Escherichia coli</i> disintegrates cell walls of gram-positive bacteria, as proven by transmission electron and atomic force microscopy.","authors":"Matthias Müller, Sigrid Mayrhofer, Wisnu Arfian A Sudjarwo, Martin Gibisch, Christopher Tauer, Eva Berger, Cécile Brocard, José L Toca-Herrera, Gerald Striedner, Rainer Hahn, Monika Cserjan-Puschmann","doi":"10.1128/jb.00456-24","DOIUrl":"10.1128/jb.00456-24","url":null,"abstract":"<p><p>Plectasin, an antimicrobial peptide, was initially isolated from the saprophytic fungus <i>Pseudoplectania nigrella</i>. This peptide, a member of the cysteine-stabilized α-helix and β-sheet family, has demonstrated potent antimicrobial activity against gram-positive pathogens, including strains resistant to conventional antibiotics. Our CASPON platform process enables the production of substantial quantities of plectasin, facilitating investigations on the activity and the mode of action of this recombinantly produced peptide. To this end, we developed an activity assay that reflects the growth inhibition of selected model bacteria, allowing for statistical analysis and evaluation of reproducibility. The mode of action was investigated using transmission electron microscopy and atomic force microscopy. The latter provided new insights into alterations in the cell surface of gram-positive bacteria treated with plectasin at the single-cell level. While the cell diameter remained unaltered, the roughness increased by up to twofold, and the cell stiffness decreased by approximately one-third in the four gram-positive bacterial strains tested. Statistical analysis of these morphological changes provides further insights into the effects and efficiency of antimicrobial peptides targeting pathogen cell walls.</p><p><strong>Importance: </strong>The rise of antibiotic-resistant bacteria is a major threat to global health. Antimicrobial peptides (AMPs) offer a promising way to combat this. With the CASPON technology, we produced the AMP plectasin comprising three disulfide bonds using <i>Escherichia coli</i>. The activity of purified plectasin with and without a CASPON fusion tag was determined for four gram-positive and four gram-negative bacteria. As anticipated, only gram-positive bacteria showed a growth inhibition response to un-tagged plectasin. Plectasin treatment on gram-positive bacteria was visualized via electron microscopy. Evaluation of atomic force microscopy indicated that plectasin treatment led to increased roughness but maintained thickness. Based on our study, we assume that the CASPON technology can be employed in the future for the production and characterization of medical-grade AMPs.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0045624"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12096834/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143779951","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 TerC family metal chaperone MeeY enables surfactin export in <i>Bacillus subtilis</i>.","authors":"Bixi He, Ankita J Sachla, Sadie B Ruesewald, Daniel B Kearns, John D Helmann","doi":"10.1128/jb.00088-25","DOIUrl":"10.1128/jb.00088-25","url":null,"abstract":"<p><p>TerC family proteins are widely conserved integral membrane proteins with functions related to metal transport. In <i>Bacillus subtilis</i>, the TerC proteins MeeF and MeeY play overlapping roles in the metalation of manganese-requiring membrane and extracellular enzymes. TerC proteins interact with the secretion translocon SecYEG and metalate proteins either during or after protein translocation. Here, we demonstrate that swarming motility is dependent on MeeY. This swarming defect can be complemented extracellularly and is correlated with a loss of surfactin. Surfactin export is mediated by SwrC, an RND family efflux pump previously shown to interact with MeeY in co-immunoprecipitation studies. The amendment of the growth medium with manganese has long been known to enhance surfactin production. We suggest a model in which surfactin export is enhanced by the MeeY-dependent metalation of the surfactin lipopeptide during export.IMPORTANCE<i>Bacillus subtilis</i> produces surfactin, a powerful detergent-like compound that functions in intercellular communication, surface motility, and as a broad-spectrum antimicrobial agent. Production of surfactin, a cyclic lipopeptide, depends on a non-ribosomal peptide synthase followed by export by SwrC, a member of the resistance-nodulation-cell division (RND) family of export proteins. Here, we demonstrate that surfactin production additionally requires MeeY, a TerC family membrane protein that exports manganese ions to support the function of secreted and membrane metalloenzymes. We propose that MeeY interacts with SwrC to facilitate metal binding to the surfactin lipopeptide during export from the cell. These results may explain the long-appreciated role that divalent metal ions play in surfactin production during industrial fermentation.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0008825"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12096827/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144003846","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":"Colony morphotype variation in <i>Burkholderia:</i> implications for success of applications and therapeutics.","authors":"Pauline M L Coulon, Kirsty Agnoli, Garry S A Myers","doi":"10.1128/jb.00521-24","DOIUrl":"10.1128/jb.00521-24","url":null,"abstract":"<p><p>The <i>Burkholderia</i> genus includes both environmental and pathogenic isolates known for their phenotypic plasticity and adaptability. <i>Burkholderia</i> spp. are intrinsically resistant to many antibiotics, often requiring prolonged therapies during infection. A key feature of <i>Burkholderia</i> spp. is colony morphotype variation (CMV), which allows for rapid adaptation to environmental changes and influences virulence, antibiotic resistance, and pathogenicity by impacting the expression of key virulence factors such as lipopolysaccharides, extracellular DNA, efflux pumps, and flagella. While alternative treatments, such as vaccines and phage therapies, hold promise, CMV has the potential to undermine their efficacy by modifying essential therapeutic targets. Despite its importance, the prevalence and underlying mechanisms of CMV remain poorly understood, leaving critical gaps in our knowledge that may hinder the development of sustainable solutions for managing <i>Burkholderia</i> infections. Addressing these gaps is crucial not only for improving infection management but also for enabling the safe reuse of <i>Burkholderia</i> in biotechnology, where their plant growth-promoting and bioremediation properties are highly valuable. Our goal is to raise awareness within the scientific community about the significance of CMV in <i>Burkholderia</i>, highlighting the urgent need to uncover the mechanisms driving CMV. A deeper understanding of CMV's role in virulence and resistance is essential to developing robust, long-term therapeutic strategies.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0052124"},"PeriodicalIF":2.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12096841/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144006767","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 CarSR two-component system directly controls <i>radD</i> expression as a global regulator that senses bacterial coaggregation in <i>Fusobacterium nucleatum</i>.","authors":"Bibek G C, Chenggang Wu","doi":"10.1128/jb.00529-24","DOIUrl":"10.1128/jb.00529-24","url":null,"abstract":"<p><p>Two-component systems (TCS) enable bacteria to sense and respond to environmental signals, facilitating rapid adaptation. <i>Fusobacterium nucleatum</i>, a key oral pathobiont, employs the CarSR TCS to modulate coaggregation with various gram-positive partners by regulating the expression of <i>radD</i>, encoding a surface adhesion protein, as revealed by RNA-Seq analysis. However, the direct regulation of the <i>radD</i>-containing operon (<i>radABCD</i>) by the response regulator CarR, the broader CarR regulon, and the signals sensed by this system remain unclear. In this study, chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-seq) identified approximately 161 CarR-enriched loci across the genome and a 17 bp consensus motif that likely serves as the CarR-binding site. Notably, one such binding motif was found in the promoter region of the <i>radABCD</i> operon. The interaction of CarR with this binding motif was further validated using electrophoretic mobility shift assays, mutagenesis, and DNase I footprinting analyses. Beyond regulating <i>radABCD</i>, CarR directly controls genes involved in fructose and amino acid (cysteine, glutamate, lysine) utilization, underscoring its role as a global regulator in <i>F. nucleatum</i>. Lastly, we discovered that RadD-mediated coaggregation enhances <i>radD</i> expression, and deletion of <i>carS</i> abolished this enhancement, suggesting that coaggregation itself serves as a signal sensed by this TCS. These findings provide new insights into the CarR regulon and the regulation of RadD, elucidating the ecological and pathogenic roles of <i>F. nucleatum</i> in dental plaque formation and disease processes.IMPORTANCE<i>Fusobacterium nucleatum</i> is an essential member of oral biofilms acting as a bridging organism that connects early and late colonizers, thus driving dental plaque formation. Its remarkable ability to aggregate with diverse bacterial partners is central to its ecological success, yet the mechanisms it senses and responds to these interactions remain poorly understood. This study identifies the CarSR two-component system as a direct regulator of RadD, a major adhesin mediating coaggregation, and reveals its role in sensing coaggregation as a signal. These findings uncover a novel mechanism by which <i>F. nucleatum</i> dynamically adapts to polymicrobial environments, offering new perspectives on biofilm formation and bacterial communication in complex oral microbial ecosystems.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0052924"},"PeriodicalIF":2.7,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144110881","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":"Community living causes changes in metabolic behavior and is permitted by specific growth conditions in two bacterial co-culture systems.","authors":"Elizabeth Ellis, Sam Fulte, Skyler Boylan, Alaina Flory, Katherine Paine, Sophia Lopez, Grace Allen, Kanwar Warya, Javier Ortiz-Merino, Sadie Blacketer, Samantha Thompson, Sierra Sanchez, Kayla Burdette, Audrey Duchscherer, Nick Pinkham, Joseph D Shih, Lilah Rahn-Lee","doi":"10.1128/jb.00075-25","DOIUrl":"https://doi.org/10.1128/jb.00075-25","url":null,"abstract":"<p><p>Although bacteria exist in complex microbial communities in the environment, their features and behavior are most often studied in monoculture. While environmental enrichments or complex co-cultures with tens or hundreds of members might more accurately represent the natural communities of bacteria, we sought to create simple pairs of organisms to learn what conditions create successful co-culture and how bacteria change transcriptionally when a partner species is present. We grew two pairs of organisms in co-culture, <i>Pseudomonas aeruginosa</i> and <i>Escherichia coli</i> and <i>Lacticaseibacillus rhamnosus</i> and <i>Bacteroides thetaiotaomicron</i>. At first, both co-cultures failed, with one organism outcompeting the other. However, through manipulating media and environmental conditions, we created co-cultures with stable member ratios over many generations for each community. We then show that changes in the expression of metabolic genes are present in all studied species, with key catabolic and anabolic pathways often upregulated in the presence of another organism. These changes in gene expression fail to occur in conditions that will not lead to successful co-culture, suggesting they are essential for adapting to and surviving in the presence of others.</p><p><strong>Importance: </strong>In 1882, Robert Koch and Fanny Hesse developed the agar plate, which enabled microbiologists to separate individual microbial cells from each other and create monocultures of a single strain of bacteria. This powerful tool has been used in the almost 150 years since to develop a robust understanding of how bacterial cells are structured, how they manage and process their information, and how they respond to the environment to produce behaviors that match their circumstances. We were curious about how the behavior of bacteria, as measured by their gene expression, changes between well-studied monoculture conditions and co-culture. We found that only specific growth conditions permit co-culture and that bacteria change their metabolic strategies in the presence of a partner.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0007525"},"PeriodicalIF":2.7,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144006700","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}