Journal of Bacteriology最新文献

{"title":"<i>Anabaena</i>, a multicellular model for cyanobacterial cell biology and biotechnology.","authors":"Enrique Flores, Ignacio Luque, Rocío López-Igual","doi":"10.1128/jb.00376-26","DOIUrl":"https://doi.org/10.1128/jb.00376-26","url":null,"abstract":"<p><p>Heterocyst-forming cyanobacteria (order Nostocales) are a monophyletic group of organisms that grow as filaments usually made of dozens to hundreds of cells (termed vegetative cells) that can perform oxygenic photosynthesis. Under combined nitrogen deficiency, some cells in the filament differentiate into N₂-fixing heterocysts, which do not produce oxygen and, indeed, keep a microoxic environment appropriate for the expression and functioning of the N₂-fixing enzyme, nitrogenase. Thus, in the diazotrophic filament, oxygenic photosynthesis and N₂ fixation are segregated into two different cell types, vegetative cells and heterocysts, which require intercellular molecular exchange to feed each other with fixed nitrogen and reduced carbon, respectively. The current understanding of heterocyst biology, including regulation of heterocyst differentiation, which also involves intercellular signaling, is the result of studying mainly a few strains of the genus <i>Anabaena</i>. Here, we review the classical studies that established <i>Anabaena</i> as a model for the Nostocales and clarified the basics of N₂ fixation in these organisms. Then, we show how molecular genetics came into the scene and how it was complemented by genomic analysis. This, together with the introduction of modern cell biology approaches, led to a renewed understanding of cellular differentiation and unraveled a system for intercellular communication that is unique in the biological world. In turn, the new accumulated knowledge on <i>Anabaena</i> physiology and genetics makes these organisms an excellent system for the development of new synthetic biology tools that will be crucial for their use in biotechnology.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0037626"},"PeriodicalIF":3.8,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149227811","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 transcriptional repressor co-regulatory network integrates iron homeostasis and mycobacterial stress tolerance to oxidative stress.","authors":"Khushboo Mehta, Kajal, Harsh Goar, Bhanwar Bamniya, Dibyendu Sarkar","doi":"10.1128/jb.00484-26","DOIUrl":"https://doi.org/10.1128/jb.00484-26","url":null,"abstract":"<p><p>A hallmark of <i>Mycobacterium tuberculosis</i> survival and proliferation within the host is attributable to the effective stress response of the pathogen against hostile environmental conditions. Although controlled iron (Fe) uptake and maintenance of Fe homeostasis are closely associated with intracellular survival of mycobacteria, the underlying mechanism that accounts for the interdependence of mycobacterial Fe regulation and oxidative stress response remains unknown. In this study, we discovered that Fe accumulation connects intra-bacterial redox environment via the <i>phoP</i> locus. Gene expression analyses coupled with genetic, biochemical, and transcriptomic studies uncover a distinct mechanism that utilizes Lsr2 and the virulence regulator PhoP to modulate transcriptional control of the major Fe storage protein-encoding gene <i>bfrB</i>. Remarkably, regulated expression of <i>bfrB</i> determines bacterial tolerance to oxidative stress and its intracellular survival. Although both regulators could independently influence <i>bfrB</i> expression, the most fundamental insights are derived from the inhibition of Lsr2 binding at the <i>bfrB</i> regulatory region of the <i>phoP</i>-KO mutant strain owing to Lsr2-PhoP protein-protein interactions. Building on these results, we proposed a model suggesting how Lsr2-PhoP interaction, or lack thereof, contributes to stress-specific regulation of <i>bfrB</i> expression. Collectively, these results uncover a key mechanism integrating Fe accumulation to oxidative stress response, an essential pathogenic determinant of <i>M. tuberculosis</i>.IMPORTANCEWhile the availability of Fe remains essential for <i>Mycobacterium tuberculosis</i> infection and replication of the pathogen in human macrophages, Fe may be harmful as it catalyzes the generation of toxic reactive oxygen species from products of aerobic respiration to induce oxidative stress. Although interdependence of mycobacterial Fe regulation and oxidative stress response has been reported, the mechanism connecting Fe acquisition and oxidative stress response is yet to be fully understood. Results reported in this study identify and elaborate on a new mechanism of regulation of expression of the major mycobacterial Fe storage protein, which determines bacterial tolerance to oxidative stress and impacts intracellular survival of the pathogen. We demonstrate that the virulence-associated <i>phoP</i> locus controls Fe accumulation and contributes to the intra-bacterial redox environment. The results uncover a distinctly different transcriptional control mechanism of the major Fe storage protein requiring a co-repressor-dependent regulatory circuit, including nucleoid-associated protein Lsr2 and the virulence regulator PhoP. Together, these results unveil a unique mechanism of stress-specific gene expression, which integrates Fe homeostasis to oxidative stress response, an essential pathogenic determinant of <i>M. tuberculosis</i>.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0048426"},"PeriodicalIF":3.8,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149227845","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":"Contribution of PonA2 to biofilm and colony formation independent of its catalytic domains in <i>Mycobacterium smegmatis</i>.","authors":"Bryan A Montero-Gutierrez, Jathin K Bande, Mercedes D Stites, Takehiro Kado","doi":"10.1128/jb.00301-26","DOIUrl":"https://doi.org/10.1128/jb.00301-26","url":null,"abstract":"<p><p>Biofilm and colony growth create microenvironments that require coordinated localization and function of cell envelope components. However, the mechanisms by which membrane organization contributes to cell envelope organization during multicellular growth remain poorly understood. <i>Mycobacterium smegmatis</i> contains an inner membrane domain (IMD) at the subpolar regions of the cell that contributes to cell envelope synthesis. Prior research identified PonA2 as important for <i>de novo</i> formation of distinct plasma membrane domains during planktonic growth. PonA2 is a penicillin-binding protein with transglycosylase (TG) and transpeptidase (TP) activities involved in peptidoglycan synthesis. To investigate the role of PonA2 during colony and pellicle biofilm growth, wild-type, Δ<i>ponA2</i>, the complement strain (c<i>ponA2</i>), and catalytically inactive PonA2 variants (TG-, TP-, and TG-/TP-) were analyzed. Subpolar IMD localization was maintained in wild-type cells during both colony and pellicle biofilm growth, demonstrating that IMD localization is not exclusive to planktonic growth. Loss of <i>ponA2</i> resulted in smooth colony and early pellicle biofilm architecture and was associated with reduced abundance of trehalose monomycolate, trehalose dimycolate, and glycopeptidolipids. Δ<i>ponA2</i> cells in colony growth exhibited shortened cell morphology and lacked detectable IMD localization, whereas Δ<i>ponA2</i> cells in pellicle biofilm growth retained bacillary morphology and subpolar IMD localization. In contrast, the catalytically inactive PonA2 variants maintained rugose multicellular architecture, bacillary morphology, and subpolar IMD localization similar to that of wild-type. Together, these findings identify a previously unrecognized noncatalytic role for PonA2 in maintaining normal colony and pellicle biofilm development in <i>M. smegmatis</i>.IMPORTANCEPlanktonic, pellicle biofilm, and colony growth expose mycobacteria to distinct environmental conditions that can affect cell-envelope organization and survival. Prior research has shown that mycobacteria form subpolar plasma membrane domains that support polar cell elongation in planktonic growth, but it remains unclear whether this organization is conserved in multicellular biofilm and colony growth, where cells experience nutrient and oxygen gradients and altered cell-to-cell interactions. Our current study analyzed the plasma membrane domain formation across the two growth states and showed that membrane domain localization is conserved, while the mechanisms required to maintain these domains differ depending on growth conditions. These findings suggest that mycobacteria use growth state-specific mechanisms to coordinate membrane organization.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0030126"},"PeriodicalIF":3.8,"publicationDate":"2026-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149182113","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":"Thank you to our recently retired editors Joe Bondy-Denomy and Tina Henkin.","authors":"George A O'Toole","doi":"10.1128/jb.00507-26","DOIUrl":"https://doi.org/10.1128/jb.00507-26","url":null,"abstract":"","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0050726"},"PeriodicalIF":3.8,"publicationDate":"2026-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149182051","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":"Correction for Robin et al., \"The CpxAR signaling system confers a fitness advantage for flea gut colonization by the plague bacillus\".","authors":"Brandon Robin, Amélie Dewitte, Véronique Alaimo, Cecile Lecoeur, François Pierre, Gabriel Billon, Florent Sebbane, Sébastien Bontemps-Gallo","doi":"10.1128/jb.00426-26","DOIUrl":"https://doi.org/10.1128/jb.00426-26","url":null,"abstract":"","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0042626"},"PeriodicalIF":3.8,"publicationDate":"2026-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149182093","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 virulence regulator ToxT influences <i>Vibrio cholerae</i> motility through the expression of the methyl-accepting chemoreceptors AcfB and TcpI.","authors":"Carlos Candanosa, Michael Cole Carter, Venus Stanton, Mark Eppinger, Karl E Klose","doi":"10.1128/jb.00425-26","DOIUrl":"https://doi.org/10.1128/jb.00425-26","url":null,"abstract":"<p><p><i>Vibrio cholerae</i> is the causative agent of the human diarrheal disease cholera. Previous studies identified \"hyperswarming\" (HS) mutant <i>V. cholerae</i> with enhanced motility and decreased virulence factor expression, but the genetic basis of HS was unknown. Through whole-genome sequencing, we have identified point mutations within <i>toxT</i>, which encodes the master virulence regulator, as being responsible for the HS phenotype. These mutations are loss of function, and they eliminate transcription of cholera toxin and toxin-coregulated pilus genes. Using single-cell video tracking, these HS strains were also observed to exhibit enhanced motility/chemotaxis (increased speed and decreased directional change). Two methyl-accepting chemoreceptors (methyl-accepting chemotaxis proteins), AcfB and TcpI, are positively regulated by ToxT, and expression of both AcfB and TcpI within HS mutants restores wild-type motility. Moreover, a <i>V. cholerae</i> strain with a hyperactive ToxT (N106A) exhibits reduced motility (decreased speed and increased directional change), and knocking out <i>acfB</i> and <i>tcpI</i> in this strain restores wild-type motility. AcfB and TcpI localize to the bacterial cell poles, suggesting they incorporate into the chemotaxis arrays to modulate swimming behavior. Our findings demonstrate that the absence of the ToxT-dependent MCPs AcfB and TcpI is responsible for the HS phenotype, demonstrating a direct role of ToxT in the swimming behavior of <i>V. cholerae</i>.IMPORTANCE<i>Vibrio cholerae</i> causes the human diarrheal disease cholera, and the master virulence regulator ToxT is responsible for the expression of the most important virulence factors, cholera toxin and the toxin-coregulated pilus, necessary for disease. Motility is also important for the bacteria to cause disease, and in this study, we provide evidence that ToxT also modulates motility, providing a regulatory link between motility and the other virulence factors required for the pathogenic lifestyle of <i>V. cholerae</i>.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0042526"},"PeriodicalIF":3.8,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149182078","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 evolution of <i>Brucella</i> as a model intracellular pathogen.","authors":"Jeannette E Farnham, Sean Crosson","doi":"10.1128/jb.00404-26","DOIUrl":"https://doi.org/10.1128/jb.00404-26","url":null,"abstract":"<p><p><i>Brucella</i> species are intracellular bacterial pathogens that cause brucellosis, one of the most common zoonoses worldwide. This review traces how <i>Brucella</i>, first discovered in the 19th century through investigations of human and bovine disease, became a modern experimental model system. Work on <i>Brucella</i> has illuminated how intracellular bacteria evade and adapt to host defenses and how they remodel host cell biology to establish a replicative niche. It has also yielded insights that extend beyond pathogenesis into bacterial cell envelope architecture and development. Though long regarded as a small, homogeneous group of mammalian pathogens, the genus has expanded in recent years as \"non-classical\" <i>Brucella</i> have been isolated from unexpected animal hosts, opening new opportunities to understand the fascinating host preferences and evolutionary history of these closely related Alphaproteobacteria. More than a century after their discovery, <i>Brucella</i> species remain versatile models for the study of intracellular infection, bacterial cell biology, and physiology, and the evolution of host association.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0040426"},"PeriodicalIF":3.8,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149182105","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":"Molecular mechanisms and regulatory networks governing <i>Yersinia</i> biofilm formation and host adaptation.","authors":"Haisheng Wu, Hailian Wu, Wenxuan Peng, Yiquan Zhang, Qingwen Zhang","doi":"10.1128/jb.00418-26","DOIUrl":"https://doi.org/10.1128/jb.00418-26","url":null,"abstract":"<p><p>The genus <i>Yersinia</i> includes three human pathogens-<i>Y</i>. <i>pestis</i>, <i>Y. pseudotuberculosis</i>, and <i>Y. enterocolitica</i>-where biofilm formation plays distinct roles in transmission and environmental persistence. All three species share the core biofilm machinery-the <i>hmsHFRS</i> operon, encoding enzymes for poly-β-1,6-N-acetylglucosamine (PNAG) exopolysaccharide production, and the c-di-GMP signaling controlling this production-but their regulatory networks and biofilm outputs differ. Transcriptional control of <i>hms</i> involves an integrated network that includes the Rcs phosphorelay (reshaped by <i>rcsA</i> pseudogenization), PhoP/PhoQ, EnvZ/OmpR, BarA/UvrY, Fur/Zur, CRP-cAMP, RovM/RovA, and multiple sigma factors. Post-transcriptionally, the Hfq-sRNA and CsrA-CsrB/CsrC systems modulate gene expression; the latter is directly validated in <i>Y. pestis</i> and <i>Y. pseudotuberculosis</i>, whereas its role in <i>Y. enterocolitica</i> is inferred from genomic conservation. At the translational and enzymatic levels, polyamines sustain Hms protein production, while redox signals govern the HmsC-HmsD disulfide switch, controlling diguanylate cyclase activity. This multi-layer architecture ensures that biofilm output is tuned to species-specific ecological niches. In host adaptation, <i>Y. pestis</i> transitioned from a foodborne enteric pathogen to a flea-borne lifestyle through key genetic events-acquisition of <i>ymt</i>, pseudogenization of <i>rcsA</i>, inactivation of <i>y2909</i>/<i>y3389,</i> and <i>ureD</i>-which are not shared with <i>Y. pseudotuberculosis</i> or <i>Y. enterocolitica</i>, thereby explaining their different biofilm-dependent transmission strategies. Studies in <i>Caenorhabditis elegans</i> have identified host O-glycosylation modifications as receptors for biofilm attachment. This review summarizes progress on the molecular mechanisms, regulatory networks, and host-adaptive functions of <i>Yersinia</i> biofilm formation and proposes future research directions to address knowledge gaps. Future priorities include the identification of c-di-GMP effectors, flea-specific signals, 3D biofilm imaging, and CRISPR-based detection.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0041826"},"PeriodicalIF":3.8,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149182062","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":"Anti-mycobacterial activity of phage-encoded lysterases.","authors":"Jindanuch Maneekul, Krista G Freeman, Elizabeth D Amarh, Julia M Kovalski, Emma Skeel, Manisha Vannan, Matthew T Montgomery, Casey Moyer, Rebecca A Garlena, Amit K Singh, Pallavi Ghosh, Anil K Ojha, Graham F Hatfull","doi":"10.1128/jb.00410-26","DOIUrl":"https://doi.org/10.1128/jb.00410-26","url":null,"abstract":"<p><p><i>Mycobacterium abscessus</i> is a non-tuberculous <i>Mycobacterium</i> (NTM) that is often associated with respiratory infections in persons with cystic fibrosis. High levels of antibiotic resistance make <i>M. abscessus</i> infections difficult to treat, highlighting the urgent need for alternative therapeutic strategies. Mycobacteriophage therapy-treatment of infections with viruses that infect <i>Mycobacterium</i> hosts-shows considerable promise, but the narrow host specificity of the current mycobacteriophage repertoire limits this approach to personalized therapies. Here, we characterize the anti-<i>M</i>. <i>abscessus</i> activity of mycobacteriophage-encoded Lysin B enzymes (lysterases). Lysterases are serine-esterases that cleave the ester bonds linking mycolic acids to either arabinogalactan or trehalose in the mycobacterial cell envelope to complete the lysis process. In this study, we explored their ability to kill a spectrum of clinically isolated <i>M. abscessus</i> strains when administered exogenously. Six phylogenetically distinct lysterases were purified, characterized on the surrogate <i>M. smegmatis</i>, and their activity against a diverse panel of 24 <i>M. abscessus</i> clinical strains was assessed. The enzymes exhibit a range of activities against these strains, but most have broad-spectrum activity with only minor variations among the <i>M. abscessus</i> isolates. However, the activities can be quite potent, resulting in up to six orders of magnitude of reduction in viability within 4 h with one activity unit of the enzymes, and act synergistically with amikacin. Overall, mycobacteriophage-encoded lysterases show considerable potential for antimycobacterial control, especially for topical applications.IMPORTANCE<i>Mycobacterium</i> infections are clinically challenging, and there is a high failure of resolving <i>Mycobacterium abscessus</i> infections using antibiotics. Mycobacteriophages show promise in treating <i>M. abscessus</i> infections, but there is substantial variation among clinical isolates in their phage infection profiles. Mycobacteriophages are unusual in coding for lysis enzymes-lysterases-that target cell wall exposed constituents, and these can have potential antibacterial activity. Exploring the vast sequence diversity of thousands of phage-encoded lysterases identifies a subset that was expressed, purified, and tested for their ability to kill a broad range of <i>M. abscessus</i> clinical strains. Lysterases with the broadest and greatest activity offer substantial potential for treatment of <i>M. abscessus</i> infection, especially where they display synergism with current antibiotics.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0041026"},"PeriodicalIF":3.8,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149182018","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":"Structural basis for ITP-selective hydrolysis by a CRISPR-associated Nudix hydrolase.","authors":"Wanqian Wu, Shenglan Xia, Duo Li, Junchao Lin, Chen Cao, Jianping Kong, Meiling Lu, Yibei Xiao, Zhaoxing Li","doi":"10.1128/jb.00280-26","DOIUrl":"https://doi.org/10.1128/jb.00280-26","url":null,"abstract":"<p><p>The nucleoside diphosphates linked to moiety-X (Nudix) hydrolases are a superfamily of proteins defined by the characteristic Nudix box sequence, most of which are involved in clearing the cell of potentially deleterious metabolites and in preventing the accumulation of metabolic intermediates. The Nudix hydrolase associated with CRISPR-Cas-associated adenosine deaminases (CAAD) from <i>Limisphaera ngatamarikiensis</i> (<i>Lng</i>NH) mitigates CAAD-induced toxicity by hydrolyzing ITP to IMP and pyrophosphate. Here, we determined crystal structures of <i>Lng</i>NH in the apo form and in complex with ITP using catalytic mutants and validated key interactions by site-directed mutagenesis. The hypoxanthine of ITP is deeply buried in a hydrophobic pocket and engages a distinct hydrogen-bond network, whereas the triphosphate tail is coordinated by conserved residues and divalent metal ions. Together, these findings provide a structural framework for CAAD-linked nucleotide sanitization and suggest that CRISPR-associated Nudix hydrolases function as local self-protection modules that limit toxicity from noncanonical inosine nucleotides.IMPORTANCENucleotide quality-control enzymes protect cells from harmful metabolic by-products. Here, we characterize a CRISPR-associated nucleoside diphosphates linked to moiety-X (Nudix) hydrolase that removes ITP, a toxic noncanonical nucleotide generated during antiviral defense. Biochemical and structural analyses show how this enzyme specifically recognizes and hydrolyzes ITP while avoiding related cellular nucleotides. Our findings suggest that CRISPR-associated nucleotide deaminase systems require \"self-protection\" mechanisms to prevent damage from their own antiviral activities. These results expand our understanding of how bacteria maintain nucleotide homeostasis during immune responses and reveal an additional regulatory layer within CRISPR-associated defense systems. The structural framework reported here also provides a foundation for future studies of nucleotide sanitization enzymes in microbial physiology and antiviral immunity.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0028026"},"PeriodicalIF":3.8,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149165957","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}