Journal of Bacteriology最新文献

{"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}

{"title":"Loss of LasR function leads to decreased repression of <i>Pseudomonas aeruginosa</i> PhoB activity at physiological phosphate concentrations.","authors":"Amy Conaway, Dallas L Mould, Igor Todorovic, Deborah A Hogan","doi":"10.1128/jb.00189-24","DOIUrl":"https://doi.org/10.1128/jb.00189-24","url":null,"abstract":"<p><p>The <i>Pseudomonas aeruginosa</i> LasR transcription factor plays a role in quorum sensing (QS) across phylogenetically distinct lineages. However, isolates with loss-of-function mutations in <i>lasR</i> (LasR- strains) are commonly found in diverse settings, including infections where they are associated with worse clinical outcomes. In LasR- strains, the LasR-regulated transcription factor RhlR can also be stimulated by the activity of the two-component system PhoR-PhoB in low-inorganic phosphate (Pi) conditions. Here, we demonstrate a novel link between LasR and PhoB in which the absence of LasR increases PhoB activity at physiological Pi concentrations and increases the Pi concentration necessary for PhoB inhibition. PhoB activity was also less sensitive to repression by Pi in mutants lacking different QS regulators (RhlR and PqsR) and in mutants lacking genes required for QS-induced phenazine production, suggesting that decreased phenazine production is one reason for increased PhoB activity in LasR- strains. In addition, the CbrA-CbrB two-component system, which can be more active in LasR- strains, was necessary for increased PhoB activity in LasR- strains, and loss of the CbrA-CbrB-controlled translational repressor Crc was sufficient to activate PhoB in LasR+ <i>P. aeruginosa</i>. Phenazines and CbrA-CbrB affected PhoB activity independently. The ∆<i>lasR</i> mutant also had PhoB-dependent growth advantages in the Pi-deplete medium and increased virulence-associated gene expression at physiological Pi, in part through reactivation of QS. This work suggests PhoR-PhoB activity may contribute to the fitness and virulence of LasR- <i>P. aeruginosa</i> and subsequent clinical outcomes.IMPORTANCELoss-of-function mutations in the gene encoding the <i>Pseudomonas aeruginosa</i> quorum sensing (QS) regulator LasR occur frequently and are associated with worse clinical outcomes. We have found that LasR- <i>P. aeruginosa</i> have elevated PhoB activity at physiological concentrations of inorganic phosphate (Pi). PhoB activity promotes Pi acquisition as well as the expression of QS and virulence-associated genes. Previous work has shown that PhoB induces RhlR, another QS regulator, in a LasR- mutant in low-Pi conditions. Here, we demonstrate a novel relationship wherein LasR represses PhoB activity through the production of phenazines and Crc-mediated translational repression. This work suggests PhoB activity may contribute to the increased virulence of LasR- <i>P. aeruginosa</i>.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0018924"},"PeriodicalIF":2.7,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143991148","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":"Calcium signaling controls early stage biofilm formation and dispersal in <i>Vibrio fischeri</i>.","authors":"Jeremy J Esin, Karen L Visick, Abby R Kroken","doi":"10.1128/jb.00077-25","DOIUrl":"https://doi.org/10.1128/jb.00077-25","url":null,"abstract":"<p><p>Bacterial dispersal from a biofilm is presently the least-studied step of the biofilm life cycle. The symbiotic bacterial species <i>Vibrio fischeri</i> is a model organism for studying biofilms relevant to a eukaryotic host; however, methodology is lacking to readily study the dispersal of this microbe from biofilms formed in the lab. Here, we adapted a time-lapse assay to visualize biofilm dispersal by <i>V. fischeri</i>. We observed biofilm formation and dispersal for multiple <i>V. fischeri</i> isolates, which displayed a variety of biofilm architecture phenotypes and dispersal dynamics. We then investigated <i>V. fischeri</i> strain ES114 using genetic tools and mutants available for this strain. ES114 exhibited calcium-dependent biofilm formation followed by a rapid (less than 10 min) coordinated dispersal event that occurred approximately 5 h from the experimental start. Biofilm dispersal was largely independent of the dispersal-promoting protease encoded by <i>lapG</i>. Although we found no role under our conditions for either biofilm formation or dispersal for several other factors including polysaccharides and autoinducers, we determined that biofilm formation was enhanced, and dispersal was delayed, with increased concentrations of calcium. Furthermore, biofilm formation depended on the calcium-responsive diguanylate cyclase (DGC) CasA, and dispersal could be modulated by overexpressing CasA. Our work has thus developed a new tool for the <i>V. fischeri</i> field and uncovered a key role for calcium signaling and c-di-GMP in early biofilm formation and dispersal in <i>V. fischeri</i>.</p><p><strong>Importance: </strong>Biofilm formation and dispersal are critical steps in both symbiotic and pathogenic colonization. Relative to biofilm formation, the process of dispersal in the model symbiont <i>Vibrio fischeri</i>, and other bacteria, is understudied. Here, we adapted an imaging assay to study early biofilm formation and the dispersal process in <i>V. fischeri</i>. We demonstrated that our assay can quantify biofilm formation and dispersal over time, can reveal phenotypic differences in diverse natural wild-type isolates, and is sensitive enough to investigate the impact of environmental factors. Our data confirm that calcium is a potent biofilm formation signal and identify the diguanylate cyclase CasA as a key regulator. This work leads the way for more in-depth research about unknown mechanisms of biofilm dispersal.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0007725"},"PeriodicalIF":2.7,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143981983","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":"<i>Haloferax volcanii</i>: a versatile model for studying archaeal biology.","authors":"Mechthild Pohlschroder, Stefan Schulze, Friedhelm Pfeiffer, Yirui Hong","doi":"10.1128/jb.00062-25","DOIUrl":"https://doi.org/10.1128/jb.00062-25","url":null,"abstract":"<p><p>Archaea, once thought limited to extreme environments, are now recognized as ubiquitous and fundamental players in global ecosystems. While morphologically similar to bacteria, they are a distinct domain of life and are evolutionarily closer to eukaryotes. The development of model archaeal systems has facilitated studies that have underscored unique physiological, biochemical, and genetic characteristics of archaea. <i>Haloferax volcanii</i> stands out as a model archaeon due to its ease of culturing, ability to grow on defined media, amenability to genetic and biochemical methods, as well as the support from a highly collaborative community. This haloarchaeon has been instrumental in exploring diverse aspects of archaeal biology, ranging from polyploidy, replication origins, and post-translational modifications to cell surface biogenesis, metabolism, and adaptation to high-salt environments. The extensive use of <i>Hfx. volcanii</i> further catalyzed the development of new technologies and databases, facilitating discovery-driven research that offers significant implications for biotechnology, biomedicine, and core biological questions.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0006225"},"PeriodicalIF":2.7,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143972476","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":"CRISPRi-mediated repression of three <i>cI</i> repressors induces the expression of three related <i>Neisseria gonorrhoeae</i> bacteriophages.","authors":"Wendy E Geslewitz, H Steven Seifert","doi":"10.1128/jb.00049-25","DOIUrl":"https://doi.org/10.1128/jb.00049-25","url":null,"abstract":"<p><p>The <i>Neisseria gonorrhoeae</i> FA1090 isolate encodes nine prophage islands (Ngoɸ1-9). Ngoɸ1-3 contain genes consistent with a <i>Siphoviridae</i>-dsDNA bacteriophage (phage). Saturating transposon-sequencing screens using two different <i>N. gonorrhoeae</i> isolates predicted that multiple prophage genes were essential, including three putative transcriptional repressors: <i>ngo0479</i> (present in Ngoɸ1), <i>ngo1116</i> (present in Ngoɸ2), and <i>ngo1630</i> (present in Ngoɸ3). All three genes display homology to the Lambda phage <i>cI</i>, a regulator important for maintaining the lysogenic state and inhibiting lytic induction, but these proteins are not close paralogs. Using a <i>Neisseria lactamica</i>-derived Type I-C CRISPR-interference system, we show that these <i>cI</i> orthologs are essential, as the knockdown of each gene results in bacterial death. We determined that the repression of the three <i>cI</i> orthologs resulted in the significant induction of phage gene expression. Finally, we detected <i>Siphoviridae</i>-like phage particles released from <i>N. gonorrhoeae</i> following repression of <i>ngo0479</i>, <i>ngo1116</i>, or <i>ngo1630</i>. We hypothesize that these <i>cI</i> orthologs are critical for preventing phage lytic infection and cell death and allow <i>N. gonorrhoeae</i> to benefit from the carriage and expression of prophage genes.IMPORTANCEBacteriophage, or phage, are bacteria-infecting viruses and are the most abundant natural entities in the world. Here, we report that <i>Neisseria gonorrhoeae</i>'s three most complete double-stranded DNA prophage islands each encode essential and related transcriptional repressors. CRISPRi-mediated repression of these transcriptional repressors leads to a significant increase in prophage gene expression and phage induction. This study marks an important initial step in studying the interaction between <i>N. gonorrhoeae</i> and its resident phage.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0004925"},"PeriodicalIF":2.7,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143991585","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":"FleQ finetunes the expression of a subset of BrlR-activated genes to enable antibiotic tolerance by <i>Pseudomonas aeruginosa</i> biofilms.","authors":"Victoria I Oladosu, Karin Sauer","doi":"10.1128/jb.00503-24","DOIUrl":"https://doi.org/10.1128/jb.00503-24","url":null,"abstract":"<p><p>The transcriptional regulator FleQ contributes to <i>Pseudomonas aeruginosa</i> biofilm formation by activating the expression and biosynthesis of matrix exopolysaccharides in a manner dependent on c-di-GMP. However, little is known about the role of FleQ in the antibiotic tolerance phenotype of <i>P. aeruginosa</i> biofilms. Inactivation of <i>fleQ</i> impaired biofilm formation and rendered biofilms susceptible to tobramycin and norfloxacin. The phenotypes were similar to biofilms inactivated in <i>sagS</i> encoding the orphan sensor SagS that promotes the switch from planktonic to biofilm growth via BfiSR and antibiotic tolerance via BrlR. While FleQ was found to contribute to biofilm formation independently of SagS and BfiSR, FleQ instead converged with SagS-dependent regulation at the level of BrlR. This was supported by multicopy expression of <i>sagS</i> failing to restore biofilm antibiotic tolerance by <i>ΔfleQ</i> to wild-type levels (and <i>vice versa</i>) and by biofilms formed by the <i>ΔfleQΔsagS</i> double mutant being as susceptible as <i>ΔfleQ</i> and <i>ΔsagS</i> biofilms. Increased antibiotic susceptibility was independent of BrlR abundance or BrlR DNA binding but coincided with significantly reduced transcript abundance of the BrlR-activated <i>mexCD-oprJ</i> and PA1874-77, encoding an ABC transporter previously shown to contribute to the tolerance of biofilms to tobramycin and norfloxacin. FleQ- dependent regulation of gene expression was indirect. Co-immunoprecipitation and BACTH assays indicated FleQ to interact with SagS via its HisKA-Rec domain, likely suggesting FleQ and SagS to likely work in concert to enable biofilm antibiotic tolerance<b>,</b> by finetuning the expression of BrlR activated genes.IMPORTANCEIn <i>P. aeruginosa</i>, FleQ inversely regulates the expression of genes encoding flagella and biofilm matrix components, including exopolysaccharide (Pel, Psl) in a manner dependent on the levels of c-di-GMP. Our findings expand on the role of FleQ from regulating the transition to the biofilm mode of growth to FleQ contributing to the antimicrobial tolerance phenotype of biofilms, by FleQ affecting the expression of PA1874-77, a downstream target of the SagS-dependent transcriptional regulator BrlR. Importantly, our findings suggest FleQ works in concert with SagS, likely via FleQ-SagS protein-protein interactions, to enable the formation of inherently tolerant <i>P. aeruginosa</i> biofilms.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0050324"},"PeriodicalIF":2.7,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143991588","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":"Azithromycin represses evolution of ceftazidime/avibactam resistance by translational repression of <i>rpoS</i> in <i>Pseudomonas aeruginosa</i>.","authors":"Congjuan Xu, Jie Feng, Yuchen Zhou, Huan Ren, Xiaolei Pan, Shuiping Chen, Xuehua Liu, Guanxian Li, Jinjin Li, Bin Geng, Linlin Gao, Zhihui Cheng, Yongxin Jin, Un-Hwan Ha, Shouguang Jin, Iain L Lamont, Daniel Pletzer, Weihui Wu","doi":"10.1128/jb.00552-24","DOIUrl":"https://doi.org/10.1128/jb.00552-24","url":null,"abstract":"<p><p>Antibiotic combinations can slow down resistance development and/or achieve synergistic therapeutic effects. In this study, we observed that a combined use of ceftazidime-avibactam (CZA) with azithromycin effectively repressed CZA resistance development in <i>Pseudomonas aeruginosa</i>. Transcriptome analysis revealed that subinhibitory concentrations of azithromycin reduced the expression of genes involved in stress-induced mutagenesis, including the stress response sigma factor <i>rpoS</i>. Interestingly, ribosome profiling revealed global redistribution of ribosomes by azithromycin, among which ribosome stalling was significantly intensified near the 5´ terminus of the <i>rpoS</i> mRNA. Further DNA mutational analysis revealed that azithromycin represses the translation of <i>rpoS</i> through its 5´-terminal rare codons, which in turn reduced its transcription. These <i>in vitro</i> observations have been recapitulated <i>in vivo</i> where azithromycin-repressed CZA resistance development when <i>P. aeruginosa</i> was passaged in mice. Overall, our study revealed the molecular mechanism of azithromycin-mediated repression of antibiotic resistance development, providing a promising antibiotic combination for the treatment of <i>P. aeruginosa</i> infections.IMPORTANCEAntibiotic resistance, a global public health challenge, demands the development of novel antibiotics and therapeutic strategies. Ceftazidime-avibactam (CZA) is a combination of a β-lactam antibiotic with a β-lactamase inhibitor that is effective against various gram-negative bacteria such as <i>Pseudomonas aeruginosa</i>. However, clinical CZA-resistant isolates have been reported. Here, we found that combining CZA with azithromycin can effectively suppress the development of resistance in <i>P. aeruginosa in vitro</i> and <i>in vivo</i>. Moreover, we found that azithromycin represses the translation initiation of <i>rpoS</i> through its 5´-terminal rare and less frequent codons, thereby subsequently reducing the mutational frequency of CZA resistance. Therefore, our work provides a promising antibiotic combination for the treatment of <i>P. aeruginosa</i> infections.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0055224"},"PeriodicalIF":2.7,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143992330","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":"The role of AdhE mutations in <i>Thermoanaerobacterium saccharolyticum</i>.","authors":"João Henrique T M Fabri, Angel Pech-Canul, Samantha J Ziegler, Tucker Emme Burgin, Isaiah D Richardson, Marybeth I Maloney, Yannick J Bomble, Lee R Lynd, Daniel G Olson","doi":"10.1128/jb.00015-25","DOIUrl":"https://doi.org/10.1128/jb.00015-25","url":null,"abstract":"<p><p><i>Thermoanaerobacterium saccharolyticum</i> is a thermophilic anaerobic bacterium that natively ferments a variety of hemicellulose substrates to organic acids and alcohols. It has recently been engineered to produce ethanol at high yield and titer; however, it uses a unique metabolic pathway for ethanol production that is poorly characterized. One of the distinctive aspects of this pathway is the presence of acetyl-CoA as an intermediate metabolite. In this organism, acetyl-CoA is converted to ethanol by a bifunctional AdhE enzyme. This enzyme has been a frequent target for mutations, and in many cases, the function of these mutations was unknown. Using a combination of genetic modifications, enzyme assays, and computational analysis, we have developed a better understanding of how mutations in AdhE affect ethanol production in the engineered homoethanologen strain. We identify a set of approximately interchangeable AdhE mutations (G544D, T597K, T597I, and T605I), whose function is to disrupt the activity of the alcohol dehydrogenase (ADH) domain of AdhE. This reduces NADH-linked ADH activity, which dramatically increases ethanol tolerance and changes the overall stoichiometry of acetaldehyde to ethanol conversion. Furthermore, our improved understanding of the function of these AdhE mutations calls into question a proposed feature of AdhE enzymes known as substrate channeling-direct transfer of acetaldehyde between the two domains of the AdhE enzyme. This improved the understanding of the role of AdhE mutations in <i>T. saccharolyticum</i> and provides deeper insights into the function of the unique ethanol production pathway in this organism.</p><p><strong>Importance: </strong>Many anaerobic bacteria maintain redox equilibrium by producing reduced organic compounds such as ethanol. The final two steps of ethanol production are mediated by a bifunctional enzyme, AdhE, and this enzyme is a frequent target of mutations in strains engineered for increased ethanol production. Paradoxically, these mutations increase ethanol production by eliminating the activity of one domain of the AdhE enzyme (the ADH domain). This provides additional support for a redox-imbalance theory of alcohol tolerance, which challenges the prevailing hypothesis that alcohol tolerance is associated with cell membrane effects.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0001525"},"PeriodicalIF":2.7,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144019560","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":"Maltodextrin transport in the extremely thermophilic, lignocellulose degrading bacterium <i>Anaerocellum bescii</i> (f. <i>Caldicellulosiruptor bescii</i>).","authors":"Hansen Tjo, Virginia Jiang, Jerelle A Joseph, Jonathan M Conway","doi":"10.1128/jb.00401-24","DOIUrl":"https://doi.org/10.1128/jb.00401-24","url":null,"abstract":"<p><p>Sugar transport into microbial cells is a critical, yet understudied step in the conversion of lignocellulosic biomass to metabolic products. <i>Anaerocellum bescii</i> (formerly <i>Caldicellulosiruptor bescii</i>) is an extremely thermophilic, anaerobic bacterium that readily degrades the cellulose and hemicellulose components of lignocellulosic biomass into a diversity of oligosaccharide substrates. Despite significant understanding of how this microorganism degrades lignocellulose, the mechanisms underlying its highly efficient transport of the released oligosaccharides into the cell are comparatively underexplored. Here, we identify and characterize the ATP-binding cassette (ABC) transporters in <i>A. bescii</i> governing maltodextrin transport. Utilizing past transcriptomic studies on <i>Anaerocellum</i> and <i>Caldicellulosiruptor</i> species, we identify two maltodextrin transporters in <i>A. bescii</i> and express and purify their substrate-binding proteins (Athe_2310 and Athe_2574) for characterization. Using differential scanning calorimetry and isothermal titration calorimetry, we show that Athe_2310 strongly interacts with shorter maltodextrins, such as maltose and trehalose, with dissociation constants in the micromolar range, while Athe_2574 binds longer maltodextrins, with dissociation constants in the sub-micromolar range. Using a sequence-structure-function comparison approach combined with molecular modeling, we provide context for the specificity of each of these substrate-binding proteins. We propose that <i>A. bescii</i> utilizes orthogonal ABC transporters to uptake malto-oligosaccharides of different lengths to maximize transport efficiency.</p><p><strong>Importance: </strong>Here, we reveal the biophysical and structural basis for oligosaccharide transport by two maltodextrin ATP-binding cassette (ABC) transporters in <i>Anaerocellum bescii</i>. This is the first biophysical characterization of carbohydrate uptake in this organism and establishes a workflow for characterizing other oligosaccharide transporters in <i>A. bescii</i> and similar biomass-degrading thermophiles of interest for lignocellulosic bioprocessing. By deciphering the mechanisms underlying high-affinity sugar uptake in <i>A. bescii</i>, we shed light on an underexplored step between extracellular lignocellulose degradation and intracellular conversion of sugars to metabolic products. This understanding will expand opportunities for harnessing sugar transport in thermophiles to reshape lignocellulose bioprocessing as part of a renewable bioeconomy.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0040124"},"PeriodicalIF":2.7,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143991614","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":"<i>Mycobacterium marinum</i> as a model for understanding principles of mycobacterial pathogenesis.","authors":"Aruna R Menon, Rebecca J Prest, David M Tobin, Patricia A Champion","doi":"10.1128/jb.00047-25","DOIUrl":"https://doi.org/10.1128/jb.00047-25","url":null,"abstract":"<p><p><i>Mycobacterium marinum</i> is a fish pathogen that has become a powerful and well-established model that has accelerated our understanding of the mechanisms of mycobacterial disease. <i>M. marinum</i> is a versatile surrogate for understanding the closely related human pathogen <i>M. tuberculosis</i>, which causes tuberculosis in humans. <i>M. marinum</i> has defined key mechanisms of pathogenesis, both shared with <i>M. tuberculosis</i> and unique to this species. In this review, we discuss the discovery of <i>M. marinum</i> as an occasional human pathogen, the shared aspects of pathogenesis with <i>M. tuberculosis,</i> and how <i>M. marinum</i> has been exploited as a model to define the molecular mechanisms of mycobacterial pathogenesis across several phases of infection.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0004725"},"PeriodicalIF":2.7,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144002295","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}