Journal of Bacteriology最新文献

{"title":"Beyond anaerobic respiration-new physiological roles for DmsABC and other S-/N-oxide reductases in <i>Escherichia coli</i>.","authors":"Qifeng Zhong, Marufa Nasreen, Ruizhe Yang, Michel Struwe, Bostjan Kobe, Ulrike Kappler","doi":"10.1128/jb.00463-24","DOIUrl":"https://doi.org/10.1128/jb.00463-24","url":null,"abstract":"<p><p>Sulfoxide reductases in pathogenic bacteria have recently received increasing attention for their association with virulence and survival within the host. Here, we have re-investigated the physiological role of the molybdenum-containing DmsABC dimethyl sulfoxide (DMSO) reductase from <i>Escherichia coli</i>, which has a proposed role in anaerobic respiration with DMSO. Our investigation into potential physiological substrates revealed that DmsABC efficiently reduces pyrimidine N-oxide, nicotinamide N-oxide, and methionine sulfoxide, and exposure to host cell-produced stressors such as hypochlorite or hydrogen peroxide specifically increased expression of the <i>E. coli dmsA</i> gene. <i>E. coli</i> strains lacking <i>dmsA</i> showed increased lag times in the presence of hypochlorite, and these strains also showed up to a 90% reduction in adherence to human bladder cells. Interestingly, in the presence of hypochlorite, expression of multiple alternative S-/N-oxide reductases present in <i>E. coli</i> was elevated by 2- to 4-fold in a ∆<i>dmsA</i> strain compared to the wild-type strain, suggesting functional redundancy. The phenotypes of the <i>E. coli</i> ∆<i>dmsA</i> strains were strikingly similar to ∆<i>dmsA</i> strains of the respiratory pathogen <i>Haemophilus influenzae</i>, which confirms the role of both enzymes in supporting host-pathogen interactions. We propose that this function is conserved in enzymes closely related to <i>E. coli</i> DmsABC. Our study also uncovered that the expression of many <i>E. coli</i> Mo enzymes was induced by oxidative stressors, including metals such as copper, and further work should be directed at determining the connection of these enzymes to host-pathogen interactions.IMPORTANCEBacterial urinary tract infections are debilitating and frequently recurring in human populations worldwide, and <i>Escherichia coli</i> strains are a major cause of these infections. In this study, we have uncovered a new mechanism by which <i>E. coli</i> can avoid being killed by the human immune system. The bacteria use a set of seven related enzymes that can reverse damage to essential cell components such as amino acids, vitamins, and DNA building blocks. Antibacterial compounds produced by the human immune system specifically induced the production of these enzymes, confirming that they play a role in helping <i>E. coli</i> survive during infection and making these enzymes potential future drug targets.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0046324"},"PeriodicalIF":2.7,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143752778","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":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","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":"","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":"https://doi.org/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":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","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":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A platform supporting generation and isolation of random transposon mutants in <i>Chlamydia trachomatis</i>.","authors":"Caroline Hawk, Nur Hamdzah, Zoe Dimond, Kenneth A Fields","doi":"10.1128/jb.00500-24","DOIUrl":"10.1128/jb.00500-24","url":null,"abstract":"<p><p><i>Chlamydia</i> species represent a paradigm for understanding successful obligate intracellular parasitism. Despite limited genetic malleability, development of genetic tools has facilitated the elucidation of molecular mechanisms governing infectivity. Random mutagenesis approaches provide one of the most powerful strategies available to accomplish untargeted elucidation of gene function. Unfortunately, initial progress in transposon-mediated mutagenesis of <i>Chlamydia</i> has been challenging. To increase efficiency, we developed a plasmid-based system that couples conditional plasmid maintenance with a previously described strategy leveraging inducible expression of the <i>Himar1</i>-derived C9 transposase. Our pOri-Tn(Q) construct was maintained in <i>Chlamydia trachomatis</i> cultivated with antibiotics but was rapidly cured in the absence of antibiotic selection. pOri-Tn(Q) supported transposition events when transposase expression was induced during infection. Induction was accompanied by loss of the plasmid backbone when penicillin G was used to select for only the transposable element. C9 induction during iterative passaging was used to increase the overall insertion frequency and accumulate an expanded pool of transposon mutants. The approach supported isolation of individual mutant strains from the mixed pool, and whole-genome sequencing confirmed that the recovered strains harbored single insertions.IMPORTANCE<i>Chlamydia trachomatis</i> is a prevalent human pathogen exerting a tremendous negative impact on human health. A complete understanding of how these bacteria create and maintain an intracellular niche and avoid/subvert host defense mechanisms to cause disease is lacking. The utility of transposon-mediated, random mutagenesis in supporting forward genetic studies is well established in a multitude of genetically tractable systems. This study reports the development of a plasmid-based system capable of generating mutant pools and supporting subsequent isolation of individual transposon mutants. This step is an important advance in providing a mechanism capable of supporting downstream studies interrogating chlamydial biology.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0050024"},"PeriodicalIF":2.7,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11925237/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143414280","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>Chlamydia trachomatis</i>: a model for intracellular bacterial parasitism.","authors":"Erin P Smith, Raphael H Valdivia","doi":"10.1128/jb.00361-24","DOIUrl":"10.1128/jb.00361-24","url":null,"abstract":"<p><p><i>Chlamydia</i> comprises a diverse group of obligate intracellular bacteria that cause infections in animals, including humans. These organisms share fascinating biology, including distinct developmental stages, non-canonical cell surface structures, and adaptations to intracellular parasitism. <i>Chlamydia trachomatis</i> is of particular interest due to its significant clinical importance, causing both ocular and sexually transmitted infections. The strain L2/434/Bu, responsible for lymphogranuloma venereum, is the most common strain used to study chlamydial molecular and cell biology because it grows readily in cell culture and is amenable to genetic manipulation. Indeed, this strain has enabled researchers to tackle fundamental questions about the molecular mechanisms underlying <i>Chlamydia's</i> developmental transitions and biphasic lifecycle and cellular adaptations to obligate intracellular parasitism, including characterizing numerous conserved virulence genes and defining immune responses. However, L2/434/Bu is not representative of <i>C. trachomatis</i> strains that cause urogenital infections in humans, limiting its utility in addressing questions of host tropism and immune evasion in reproductive organs. Recent research efforts are shifting toward understanding the unique attributes of more clinically relevant <i>C. trachomatis</i> genovars.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0036124"},"PeriodicalIF":2.7,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11925236/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143458087","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":"Rho-dependent termination and RNase E-mediated cleavage: dual pathways for RNA 3' end processing in polycistronic mRNA.","authors":"Heung Jin Jeon, Monford Paul Abishek N, Xun Wang, Heon M Lim","doi":"10.1128/jb.00437-24","DOIUrl":"10.1128/jb.00437-24","url":null,"abstract":"<p><p>\"Pre-full-length\" transcripts are produced at the end of the polycistronic galactose (<i>gal</i>) operon, 5' <i>galE-galT-galK-galM 3'</i>, via Rho-dependent transcription termination (RDT) and -independent transcription termination. The 3' end of the full-length <i>galETKM</i> mRNA is acquired by exonucleolytic processing of the 3'-OH ends of the pre-full-length transcripts. However, the <i>gal</i> operon produces an mRNA termed <i>galE</i> whose 3' end forms approximately 120 nucleotides downstream of the <i>galE</i> stop codon, within the subsequent gene, <i>galT</i>, thereby establishing polarity in gene expression. In this study, we investigated the molecular processes that generate the 3' end of <i>galE</i> mRNA. We discovered that the 3' ends of pre-galE mRNA are produced in the middle of <i>galT</i> as a result of the combination of two separate molecular processes-one previously reported as RDT and the other as unreported RNase E-mediated transcript cleavage. The 3' ends of pre-<i>galE</i> mRNA undergo exonucleolytic processing to the 3' end of <i>galE</i> mRNA observed <i>in vivo</i>. A hairpin structure containing an 8 bp stem and a 4-nucleotide loop, located 5-10 nucleotides upstream of the 3' ends of <i>galE</i> mRNA, blocks exoribonuclease digestion and renders transcript stability. These findings demonstrate that RNase E-contrary to its general role in mRNA degradation-produces RNA 3' ends that regulate polarity in gene expression.IMPORTANCEThis study reports the findings of two molecular mechanisms that generate the 3' ends of pre-<i>galE</i> mRNA in the <i>gal</i> operon, viz., Rho-dependent transcription termination and RNase E-mediated cleavage. These 3' ends are subsequently processed to produce stable <i>galE</i> mRNA with a hairpin structure that prevents exoribonuclease degradation. This mechanism establishes gene expression polarity by generating the 3' end of <i>galE</i> mRNA within <i>galT</i> in contrast to the usual mRNA degradation role of RNase E. The study reveals a unique role of RNase E in mRNA processing and stability.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0043724"},"PeriodicalIF":2.7,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11925234/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143515652","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":"Robust and highly efficient transformation method for a minimal mycoplasma cell.","authors":"Masaki Mizutani, John I Glass, Takema Fukatsu, Yo Suzuki, Shigeyuki Kakizawa","doi":"10.1128/jb.00415-24","DOIUrl":"10.1128/jb.00415-24","url":null,"abstract":"<p><p>Mycoplasmas have been widely investigated for their pathogenicity, as well as for genomics and synthetic biology. Conventionally, transformation of mycoplasmas was not highly efficient, and due to the low transformation efficiency, large amounts of DNA and recipient cells were required for that purpose. Here, we report a robust and highly efficient transformation method for the minimal cell JCVI-syn3B, which was created through streamlining the genome of <i>Mycoplasma mycoides</i>. When the growth states of JCVI-syn3B were examined in detail by focusing on such factors as pH, color, absorbance, colony forming unit, and transformation efficiency, it was found that the growth phase after the lag phase can be divided into three distinct phases, of which the highest transformation efficiency was observed during the early exponential growth phase. Notably, the transformation efficiency of up to 4.4 × 10^-2 transformants per cell per microgram of plasmid DNA was obtained. A method to obtain several hundred to several thousand transformants with less than 0.2 mL of culture with approximately 1 × 10⁷-10⁸ cells and 10 ng of plasmid DNA was developed. Moreover, a transformation method using a frozen stock of transformation-ready cells was established. These procedures and information could simplify and enhance the transformation process of minimal cells, facilitating advanced genetic engineering and biological research using minimal cells.</p><p><strong>Importance: </strong>Mycoplasmas are parasitic and pathogenic bacteria for many animals. They are also useful bacteria to understand the cellular process of life and for bioengineering because of their simple metabolism, small genomes, and cultivability. Genetic manipulation is crucial for these purposes, but transformation efficiency in mycoplasmas is typically quite low. Here, we report a highly efficient transformation method for the minimal genome mycoplasma JCVI-syn3B. Using this method, transformants can be obtained with only 10 ng of plasmid DNA, which is around one-thousandth of the amount required for traditional mycoplasma transformations. Moreover, a convenient method using frozen stocks of transformation-ready cells was established. These improved methods play a crucial role in further studies using minimal cells.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0041524"},"PeriodicalIF":2.7,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11925241/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143189470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quorum sensing and DNA methylation play active roles in clinical <i>Burkholderia</i> phase variation.","authors":"Pauline M L Coulon, Marie-Christine Groleau, Abderrahman Hachani, Matthew P Padula, Timothy P Stinear, Eric Déziel","doi":"10.1128/jb.00531-24","DOIUrl":"10.1128/jb.00531-24","url":null,"abstract":"<p><p>Phenotypic diversity in bacteria often results from adaptation to changing environmental conditions, exemplified by variable colony morphotypes. In <i>Burkholderia pseudomallei</i>, discrete genomic alterations and modulation of gene expression facilitate adaptation. Adapted variants of species within the <i>Burkholderia cepacia</i> complex (Bcc) often lose the pC3 virulence megaplasmid, impacting their colony morphology and their production of virulence factors. In this study, we characterize variants arising in <i>Burkholderia ambifaria</i> clinical isolates using proteomics and phenotypic tests and show that some of them have retained the pC3, indicating a distinct phase variation mechanism at play in this Bcc species. Interestingly, variants of <i>B. ambifaria</i> strains CEP0996 (pC3-null) and HSJ1 (pC3-positive) still share similarities in phenotypes controlled by the Cep quorum-sensing (QS) system. We further investigated the role of QS in <i>B. ambifaria</i> HSJ1 phase variation and confirmed that the Cep QS system is important for the emergence of variants. Given that DNA methylation is a key epigenetic factor regulating virulence factors in <i>Burkholderia cenocepacia</i>, we hypothesized that adenosine DNA methylation also governs phase variation in <i>B. ambifaria</i> HSJ1. By deleting the genes encoding putative adenosine DNA methyltransferases, we discovered that an orphan type II DNA methyltransferase inhibits the emergence of phase variants. This study is the first to demonstrate that quorum sensing and adenosine DNA methylation are two antagonistic systems independently controlling phase variation in <i>B. ambifaria</i>.IMPORTANCESome <i>Burkholderia</i> species are pathogenic to plants, animals, or humans. In immunocompromised individuals, and people suffering from cystic fibrosis, infection from the <i>Burkholderia cepacia</i> complex (Bcc) can lead to \"<i>cepacia</i> syndrome.\" In northern Australia and southeast Asia, melioidosis caused by <i>Burkholderia pseudomallei</i> is prevalent among native population, particularly among people with diabetes, chronic lung or kidney disease or alcoholism. <i>Burkholderia</i>'s phenotypic plasticity, including colony morphotype variation (CMV), enables rapid adaptation to diverse environments, enhancing its survival and pathogenicity. This study reveals phase variation as a new CMV mechanism within the Bcc group and is the first to report that quorum sensing and DNA methylation are involved in phase variation. Understanding the underlying mechanisms of CMV could lead to the development of targeted therapies against these highly antibiotic-tolerant bacteria.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0053124"},"PeriodicalIF":2.7,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11925244/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143414283","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":"Germination of <i>Bacillus</i> spores by LiCl.","authors":"James Wicander, John Gorsuch, Longjiao Chen, Rebecca Caldbeck, George Korza, Stanley Brul, Graham Christie, Peter Setlow","doi":"10.1128/jb.00510-24","DOIUrl":"10.1128/jb.00510-24","url":null,"abstract":"<p><p>Spores of <i>Bacillus subtilis</i> have been found to germinate when incubated with LiCl, but not with other monovalent or divalent metal cations. <i>Bacillus megaterium</i> spores also germinated with LiCl, but <i>B. cereus</i> spores did not. In <i>B. subtilis</i>, the LiCl germination was via the activation of spores' GerA germinant receptor (GR), and in <i>B. megaterium,</i> it was the GerU GR. Notably, LiCl germination was much slower than normal physiological germinant triggered GR germination. In <i>B. subtilis</i> spores, rates of LiCl germination were increased in spores with a more fluid IM and decreased in spores with a less fluid IM. Analyses of the GerA germinant binding site suggested that Li⁺ could bind in a specific site in the <i>B. subtilis</i> GerAB subunit where normally a Na⁺ likely binds. Importantly, NaCl strongly inhibited LiCl germination of <i>B. subtilis</i> spores, much more so than the larger cation in KCl, although neither salt inhibited L-alanine germination via the GerA GR. These findings increase the understanding of features of mechanisms of germination of <i>Bacillus</i> spores.IMPORTANCEThe ability of some bacteria to form spores upon nutrient starvation confers properties of metabolic dormancy and enhanced resistance to environmental stressors that would otherwise kill vegetative cells. Since spore-forming bacteria include several notable pathogens and economically significant spoilage organisms, insight into how spores are stimulated to germinate and form new vegetative cells is important. Here, we reveal that relatively high concentrations of the inorganic salt lithium chloride trigger the germination of <i>Bacillus subtilis</i> and <i>Bacillus megaterium</i> spores by stimulating one of the spores of each species cohort of nutrient germinant receptors. This is significant since novel germinants and increased knowledge of the germination process should provide opportunities for improved control of spores in healthcare, food, and environmental sectors.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0051024"},"PeriodicalIF":2.7,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11925240/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143515502","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":"Broken beyond repair: TA system ParE toxins mediate effective gyrase inhibition without driving resistance.","authors":"Chih-Han Tu, Shengfeng Ruan, Michelle Holt, Christina R Bourne","doi":"10.1128/jb.00416-24","DOIUrl":"10.1128/jb.00416-24","url":null,"abstract":"<p><p>DNA gyrase is an essential bacterial-specific type IIA topoisomerase that corrects DNA overwinding during transcription and replication. Compounds capable of stabilizing gyrase-mediated double-strand DNA breaks are valuable antibacterials; however, these can trigger error-prone repair, potentially inducing DNA mutations leading to antimicrobial resistance. ParE toxin proteins, which belong to a family of type II toxin-antitoxin systems, inhibit DNA gyrase and promote the persistence of double-strand DNA breaks. However, it is unclear if the ParE-induced gyrase inhibition is equivalent for all ParE family members, or if any mutations arise and can accumulate to cause antibiotic resistance. Selected chromosomal ParE toxins were examined for toxicity to their native bacterial hosts, and the frequency of mutations and impact on susceptibility to selected antibiotics were assessed. Our results show that ParE toxins from <i>Burkholderia cenocepacia</i>, <i>Mycobacterium tuberculosis</i>, <i>Pseudomonas aeruginosa</i>, and <i>Vibrio cholerae</i> exert potent toxicities toward the native cells, whereas one tested ParE toxin from <i>P. aeruginosa</i> was not toxic. The contribution to toxicity of the ParE toxin C-terminal amino acid sequences was examined using two lab-generated chimeric ParE toxins; our results demonstrate that this region did not impact the toxicity level. Our study finds that the relative potency of individual ParE toxins correlates with increases in mutation frequency. While some ParE toxins induced limited collateral sensitivity to selected antibiotics, no increases in MIC values were found. Overall, this study demonstrates the relative toxicity of different ParE toxins. Importantly, the toxicity appears to result in loss of viability before productive resistance-inducing mutations can accumulate.</p><p><strong>Importance: </strong>Toxin-antitoxin (TA) systems can halt growth or kill cells when the toxin protein engages with the host cell target. In the ParDE TA system, the toxin ParE inhibits DNA gyrase, resulting in loss of viability that phenocopies fluoroquinolone antibiotics. Our study demonstrates that ParE toxins increase the frequency of mutations, presumably by a mechanism similar to fluoroquinolone antibiotics. These increases scale to the resulting toxicity, and importantly, these mutations do not accumulate into productive antibacterial resistance. This suggests that ParE toxins are not intrinsic drivers of resistance and, if the molecular mechanism can be harnessed, could generate a new class of gyrase inhibitors.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0041624"},"PeriodicalIF":2.7,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11925232/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143542072","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}