Molecular Microbiology最新文献

{"title":"Unveiling the Coordinated Action of DesK/DesR and YvfT/YvfU to Control the Expression of an ABC Transporter in Bacillus subtilis","authors":"Pilar Fernández, Lucía Porrini, Julián Ignacio Pereyra, Daniela Albanesi, María Cecilia Mansilla","doi":"10.1111/mmi.15320","DOIUrl":"https://doi.org/10.1111/mmi.15320","url":null,"abstract":"Two-component systems (TCSs) are vital signal transduction pathways ubiquitous among bacteria, facilitating their responses to diverse environmental stimuli. In <i>Bacillus subtilis</i>, the DesK histidine kinase thermosensor, together with the response regulator DesR, constitute a TCS dedicated to membrane lipid homeostasis maintenance. This TCS orchestrates the transcriptional regulation of the <i>des</i> gene, encoding the sole desaturase in these bacteria, Δ5-Des. Additionally, <i>B. subtilis</i> possesses a paralog TCS, YvfT/YvfU, with unknown target gene(s). In this work, we show that YvfT/YvfU controls the expression of the <i>yvfRS</i> operon that codes for an ABC transporter. Interestingly, we found that this regulation also involves the action of DesK/DesR. Notably, opposite to <i>des</i>, <i>yvfRS</i> transcription is induced at 37°C and not at 25°C. Our in vivo and in vitro experiments demonstrate that both YvfU and DesR directly bind to the operon promoter region, with DesR exerting its control over <i>yvfRS</i> expression in its unphosphorylated state. Our study uncovers an intriguing case of cross-regulation where two homologous TCSs interact closely to finely tune gene expression in response to environmental cues. These findings shed light on the complexity of bacterial signal transduction systems and their critical role in bacterial adaptability.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"9 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142330268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of bb0556 Expression and Its Role During Borrelia burgdorferi Mammalian Infection","authors":"Sierra George, Connor Waldron, Christina Thompson, Zhiming Ouyang","doi":"10.1111/mmi.15319","DOIUrl":"https://doi.org/10.1111/mmi.15319","url":null,"abstract":"In <i>Borrelia burgdorferi</i>, BB0556 was annotated as a conserved hypothetical protein. We herein investigated gene expression and the importance of this protein during infection. Our data support that <i>bb0556</i> forms an operon with five other genes. A transcriptional start site and the associated σ⁷⁰-type promoter were identified in the sequences upstream of <i>bb0554</i>, and luciferase reporter assays indicated that this promoter is functional in <i>B. burgdorferi</i>. Furthermore, the sequences upstream of <i>bb0556</i> contain an internal promoter to drive gene expression. <i>bb0556</i> expression was affected by various environmental factors such as changes in temperature, pH, and cell density when <i>B. burgdorferi</i> was grown in vitro. Surprisingly, significant differences were observed for <i>bb0556</i> expression between <i>B. burgdorferi</i> strains B31-A3 and CE162, likely due to the different <i>cis-</i> and <i>trans</i>-acting factors in these strains. Moreover, <i>bb0556</i> was found to be highly expressed by <i>B. burgdorferi</i> in infected mice tissues, suggesting that this gene plays an important role during animal infection. To test this hypothesis, we generated a <i>bb0556</i> deletion mutant in a virulent bioluminescent <i>B. burgdorferi</i> strain. The mutant grew normally in the medium and displayed no defect in the resistance to environmental stresses such as reactive oxygen species, reactive nitrogen species, and osmotic stress. However, when the infectivity was compared between the mutant and its parental strain using in vivo bioluminescence imaging as well as analyses of spirochete recovery and bacterial burdens in animal tissues, our data showed that, contrary to the parental strain, the mutant was unable to infect mice. Complementation of <i>bb0556</i> in <i>cis</i> fully restored the infectious phenotype to wild-type levels. Taken together, our study demonstrates that the hypothetical protein BB0556 is a novel virulence factor essential for <i>B. burgdorferi</i> mammalian infection.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"11 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142275659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Specificity of Membrane-Associated J-Domain Protein, Caj1, in Amphotericin B Tolerance in Budding Yeast","authors":"Preeti Sagarika, Neha Dobriyal, Pakirisamy Deepsika, Avanti Vairagkar, Ankita Das, Chandan Sahi","doi":"10.1111/mmi.15318","DOIUrl":"https://doi.org/10.1111/mmi.15318","url":null,"abstract":"Hsp70:J-domain protein (JDP) machineries play pivotal roles in maintaining cellular proteostasis and governing various aspects of fungal physiology. While Hsp70 is known for its involvement in conferring tolerance to diverse antifungal drugs, the specific contribution of JDPs remains unclear. In this study, we examined the sensitivity of cytosolic JDP deletion strains of budding yeast to amphotericin B (AmB), a polyene antifungal agent widely utilized in fungal disease treatment due to its ability to disrupt the fungal plasma membrane (PM). Deleting Caj1, a PM-associated class II JDP, heightened susceptibility to AmB, and the protection conferred by Caj1 against AmB necessitated both its N-terminal J-domain and C-terminal lipid binding domain. Moreover, Caj1 deficiency compromised PM integrity as evidenced by increased phosphate efflux and exacerbated AmB sensitivity, particularly at elevated temperatures. Notably, phytosphingosine (PHS) addition as well as overexpression of <i>PMP3</i>, a positive PM integrity regulator, significantly rescued AmB sensitivity of <i>caj1Δ</i> cells. Our results align with the notion that Caj1 associates with the PM and cooperates with Hsp70 to regulate PM proteostasis, thereby influencing PM integrity in budding yeast. Loss of Caj1 function at the PM compromises PM protein quality control, thereby rendering yeast cells more susceptible to AmB.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"56 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142237016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Small Regulatory RNAs of the Rsm Clan in Pseudomonas","authors":"María Trinidad Gallegos, Matías Garavaglia, Claudio Valverde","doi":"10.1111/mmi.15313","DOIUrl":"https://doi.org/10.1111/mmi.15313","url":null,"abstract":"Bacteria of the genus <i>Pseudomonas</i> are ubiquitous on Earth due to their great metabolic versatility and adaptation to fluctuating environments and different hosts. Some groups are important animal/human and plant pathogens, whereas others are studied for their biotechnological applications, including bioremediation, biological control of phytopathogens and plant growth promotion. Notably, their adaptability is mediated by various signal transduction systems, with the post-transcriptional Gac-Rsm cascade playing a key role. This pervasive <i>Pseudomonas</i> pathway controls major transitions at the population level, such as motile/sessile lifestyle, primary/secondary metabolism or replicative/infective behaviour. A hallmark of the Gac-Rsm cascade is the participation of small, regulatory, non-coding RNAs of the Rsm clan. These RNAs are synthetised in response to cell-density-dependent autoinducer signals channelled through the GacS/GacA two-component system, and they counteract, by molecular mimicry, the translational control that RNA-binding proteins of the RsmA family exert over hundreds of mRNAs. Rsm RNAs have been investigated in a few <i>Pseudomonas</i> model species, evidencing the presence of a variable number and families of genes depending on the taxonomic clade. However, the global picture of the distribution of these riboregulators at the genus level was unknown until now. We have undertaken a comprehensive survey and annotation of the vast array of gene sequences encoding members of the Rsm RNA clan in 245 complete genomes that cover 28 phylogenomic clades across the entire genus. The properties of the different families of <i>rsm</i> genes, their phylogenetic radiation, as well as the features of their promoters and adjacent regions, are discussed. The novel insights presented in our manuscript will significantly boost research on the biology of these prevalent RNAs in understudied species of the genus <i>Pseudomonas</i> and closely related genera.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"12 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142234053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiple Effects of L-Leucine in Escherichia coli Lead to L-Leucine-Sensitive Growth in the Absence of Unphosphorylated PtsN","authors":"Neeraj Kumar, Abhijit A. Sardesai","doi":"10.1111/mmi.15317","DOIUrl":"https://doi.org/10.1111/mmi.15317","url":null,"abstract":"In <i>E. coli</i> K-12, the absence of unphosphorylated PtsN (unphospho-PtsN) has been proposed to cause an L-leucine-sensitive growth phenotype (Leu^S) by hyperactivated K⁺ uptake mediated impairment of the expression of the <i>ilvBN</i> operon, encoding subunits of the L-valine (Val)-sensitive acetohydroxyacid synthase I (AHAS I) that renders residual AHAS activity susceptible to inhibition by Leu and K⁺. This leads to AHAS insufficiency and a requirement for L-isoleucine (Ile). Herein, we provide an alternate mechanism for the Leu^S of the ∆<i>ptsN</i> mutant. Genetic and physiological studies with suppressors of the Leu^S indicate that impaired expression of the <i>ilvBN</i> operon jointly caused by the absence of unphospho-PtsN and the presence of Leu coupled to Leu-mediated repression of expression of AHAS III leads to AHAS insufficiency rendering residual AHAS activity susceptible to chronic Val stress that may be generated by exogenous Leu. Hyperactivated K⁺ uptake and an elevated α-ketobutyrate level mediate elevation of <i>ilvBN</i> expression and alleviate the Leu^S. The requirement of unphospho-PtsN as a positive regulator of <i>ilvBN</i> expression may buffer Ile biosynthesis against Leu-mediated AHAS insufficiency and protect AHAS I function from chronic endogenous Val generated by Leu and could be realized in certain environments that impair AHAS function.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"46 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142231820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Impact of YabG Mutations on Clostridioides difficile Spore Germination and Processing of Spore Substrates","authors":"Morgan S. Osborne, Joshua N. Brehm, Carmen Olivença, Alicia M. Cochran, Mónica Serrano, Adriano O. Henriques, Joseph A. Sorg","doi":"10.1111/mmi.15316","DOIUrl":"https://doi.org/10.1111/mmi.15316","url":null,"abstract":"YabG is a sporulation‐specific protease that is conserved among sporulating bacteria. <jats:italic>Clostridioides difficile</jats:italic> YabG processes the cortex destined proteins preproSleC into proSleC and CspBA to CspB and CspA. YabG also affects synthesis of spore coat/exosporium proteins CotA and CdeM. In prior work that identified CspA as the co‐germinant receptor, mutations in <jats:italic>yabG</jats:italic> were found which altered the co‐germinants required to initiate spore germination. To understand how these mutations in the <jats:italic>yabG</jats:italic> locus contribute to <jats:italic>C</jats:italic>. <jats:italic>difficile</jats:italic> spore germination, we introduced these mutations into an isogenic background. Spores derived from <jats:italic>C</jats:italic>. <jats:italic>difficile yabG</jats:italic><jats:sub>C207A</jats:sub> (a catalytically inactive allele), <jats:italic>C</jats:italic>. <jats:italic>difficile yabG</jats:italic><jats:sub>A46D</jats:sub>, <jats:italic>C</jats:italic>. <jats:italic>difficile yabG</jats:italic><jats:sub>G37E</jats:sub>, and <jats:italic>C</jats:italic>. <jats:italic>difficile yabG</jats:italic><jats:sub>P153L</jats:sub> strains germinated in response to taurocholic acid alone. Recombinantly expressed and purified preproSleC incubated with <jats:italic>E</jats:italic>. <jats:italic>coli</jats:italic> lysate expressing wild type YabG resulted in the removal of the presequence from preproSleC. Interestingly, only YabG<jats:sub>A46D</jats:sub> showed any activity toward purified preproSleC. Mutation of the YabG processing site in preproSleC (R119A) led to YabG shifting its processing to R115 or R112. Finally, changes in <jats:italic>yabG</jats:italic> expression under the mutant promoters were analyzed using a SNAP‐tag and revealed expression differences at early and late stages of sporulation. Overall, our results support and expand upon the hypothesis that YabG is important for germination and spore assembly and, upon mutation of the processing site, can shift where it cleaves substrates.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"9 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142170937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular Microbiology of Microbiomes","authors":"Pierre Santucci","doi":"10.1111/mmi.15308","DOIUrl":"https://doi.org/10.1111/mmi.15308","url":null,"abstract":"","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"97 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142170934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lactobacillus gasseri and Gardnerella vaginalis produce extracellular vesicles that contribute to the function of the vaginal microbiome and modulate host-Trichomonas vaginalis interactions.","authors":"Anastasiia Artuyants, Jiwon Hong, Priscila Dauros-Singorenko, Anthony Phillips, Augusto Simoes-Barbosa","doi":"10.1111/mmi.15130","DOIUrl":"10.1111/mmi.15130","url":null,"abstract":"<p><p>Trichomonas vaginalis is an extracellular protozoan parasite of the human urogenital tract, responsible for a prevalent sexually transmitted infection. Trichomoniasis is accompanied by a dysbiotic microbiome that is characterised by the depletion of host-protective commensals such as Lactobacillus gasseri, and the flourishing of a bacterial consortium that is comparable to the one seen for bacterial vaginosis, including the founder species Gardnerella vaginalis. These two vaginal bacteria are known to have opposite effects on T. vaginalis pathogenicity. Studies on extracellular vesicles (EVs) have been focused on the direction of a microbial producer (commensal or pathogen) to a host recipient, and largely in the context of the gut microbiome. Here, taking advantage of the simplicity of the human cervicovaginal microbiome, we determined the molecular cargo of EVs produced by L. gasseri and G. vaginalis and examined how these vesicles modulate the interaction of T. vaginalis and host cells. We show that these EVs carry a specific cargo of proteins, which functions can be attributed to the opposite roles that these bacteria play in the vaginal biome. Furthermore, these bacterial EVs are delivered to host and protozoan cells, modulating host-pathogen interactions in a way that mimics the opposite effects that these bacteria have on T. vaginalis pathogenicity. This is the first study to describe side-by-side the protein composition of EVs produced by two bacteria belonging to the opposite spectrum of a microbiome and to demonstrate that these vesicles modulate the pathogenicity of a protozoan parasite. Such as in trichomoniasis, infections and dysbiosis co-occur frequently resulting in significant co-morbidities. Therefore, studies like this provide the knowledge for the development of antimicrobial therapies that aim to clear the infection while restoring a healthy microbiome.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"357-371"},"PeriodicalIF":2.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9860987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simvastatin induces human gut bacterial cell surface genes.","authors":"Veronica Escalante, Renuka R Nayak, Cecilia Noecker, Joel Babdor, Matthew Spitzer, Adam M Deutschbauer, Peter J Turnbaugh","doi":"10.1111/mmi.15151","DOIUrl":"10.1111/mmi.15151","url":null,"abstract":"<p><p>Drugs intended to target mammalian cells can have broad off-target effects on the human gut microbiota with potential downstream consequences for drug efficacy and side effect profiles. Yet, despite a rich literature on antibiotic resistance, we still know very little about the mechanisms through which commensal bacteria evade non-antibiotic drugs. Here, we focus on statins, one of the most prescribed drug types in the world and an essential tool in the prevention and treatment of high circulating cholesterol levels. Prior work in humans, mice, and cell culture support an off-target effect of statins on human gut bacteria; however, the genetic determinants of statin sensitivity remain unknown. We confirmed that simvastatin inhibits the growth of diverse human gut bacterial strains grown in communities and in pure cultures. Drug sensitivity varied between phyla and was dose-dependent. We selected two representative simvastatin-sensitive species for more in-depth analysis: Eggerthella lenta (phylum: Actinobacteriota) and Bacteroides thetaiotaomicron (phylum: Bacteroidota). Transcriptomics revealed that both bacterial species upregulate genes in response to simvastatin that alter the cell membrane, including fatty acid biogenesis (E. lenta) and drug efflux systems (B. thetaiotaomicron). Transposon mutagenesis identified a key efflux system in B. thetaiotaomicron that enables growth in the presence of statins. Taken together, these results emphasize the importance of the bacterial cell membrane in countering the off-target effects of host-targeted drugs. Continued mechanistic dissection of the various mechanisms through which the human gut microbiota evades drugs will be essential to understand and predict the effects of drug administration in human cohorts and the potential downstream consequences for health and disease.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"372-386"},"PeriodicalIF":2.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10940213/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10234832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Space, the final frontier: The spatial component of phytoplankton-bacterial interactions.","authors":"Clara Martínez-Pérez, Sophie T Zweifel, Roberto Pioli, Roman Stocker","doi":"10.1111/mmi.15293","DOIUrl":"10.1111/mmi.15293","url":null,"abstract":"<p><p>Microscale interactions between marine phytoplankton and bacteria shape the microenvironment of individual cells, impacting their physiology and ultimately influencing global-scale biogeochemical processes like carbon and nutrient cycling. In dilute environments such as the ocean water column, metabolic exchange between microorganisms likely requires close proximity between partners. However, the biological strategies to achieve this physical proximity remain an understudied aspect of phytoplankton-bacterial associations. Understanding the mechanisms by which these microorganisms establish and sustain spatial relationships and the extent to which spatial proximity is necessary for interactions to occur, is critical to learning how spatial associations influence the ecology of phytoplankton and bacterial communities. Here, we provide an overview of current knowledge on the role of space in shaping interactions among ocean microorganisms, encompassing behavioural and metabolic evidence. We propose that characterising phytoplankton-bacterial interactions from a spatial perspective can contribute to a mechanistic understanding of the establishment and maintenance of these associations and, consequently, an enhanced ability to predict the impact of microscale processes on ecosystem-wide phenomena.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"331-346"},"PeriodicalIF":2.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141545048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}