Molecular Microbiology最新文献

{"title":"A Mobile Glycosylation Locus Modulates Cell Wall Architecture in Lactobacillus crispatus ","authors":"P. Achterberg, M. Lekkerkerker, L. Koelemeijer, S. Illidge, J. Vroom, R. Y. Hertzberger, J. Vreede, M. C. M. van Loosdrecht, R. Kort","doi":"10.1111/mmi.70112","DOIUrl":"https://doi.org/10.1111/mmi.70112","url":null,"abstract":"<jats:styled-content style=\"fixed-case\"> <jats:italic>Lactobacillus crispatus</jats:italic> </jats:styled-content> dominance in the vaginal microbiome is associated with beneficial health outcomes, yet strain‐level variation and its implications remain poorly understood. Here, we resolve the genomic context of three glycosyltransferase gene fragments (GT1‐3) previously linked with dysbiotic states. Long‐read resequencing revealed that GT1‐3 are part of a ~18.7 kb Wzx/Wzy‐dependent cell wall polysaccharide (CWPS) locus, containing several IS256‐family transposases. Serial propagation in vitro produced isolates with 4.1 kb excised via a composite transposon encompassing the GT3, UDP‐galactopyranose mutase, flippase, and hypothetical protein, demonstrating structural plasticity. Transmission electron microscopy showed a ~20%–25% thinner peptidoglycan layer in the derived strains, while FT‐IR and monosaccharide analysis indicated no gross changes. Molecular dynamics simulations suggest that GT3 contributes to the structural stability of the glycosyltransferase complex, without compromising catalytic function. Together, these findings establish the CWPS locus as a mobile, structurally plastic element that directly influences cell wall architecture in <jats:styled-content style=\"fixed-case\"> <jats:italic>L. crispatus</jats:italic> </jats:styled-content> .","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"376 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2026-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148922806","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":"α‐1,3‐Glucan Is Required for Cell Wall Integrity and Full Virulence of Colletotrichum graminicola , but Not for Evasion of PAMP ‐Triggered Immunity","authors":"Iris Gase, Lala Aliyeva‐Schnorr, Michael Melzer, Maria Ott, Julia Haufe, Matthias Menzel, Timo Engelsdorf, Christiane Rohrbach, Alan de Oliveira Silva, Lars M. Voll, Alexander S. Mickel, Maximilian Groß, Mamoru Wakayama, Holger B. Deising","doi":"10.1111/mmi.70114","DOIUrl":"https://doi.org/10.1111/mmi.70114","url":null,"abstract":"Although α‐1,3‐glucan represents a major polymer in cell walls of filamentous plant pathogenic fungi, its role in vegetative and pathogenic development is poorly understood. The maize anthracnose fungus <jats:italic>Colletotrichum graminicola</jats:italic> differentiates elaborate appressoria on the leaf surface and exhibits a hemibiotrophic lifestyle after host invasion. Promoter‐eGFP‐fusion analyses of all three α‐1,3‐glucan synthase ( <jats:italic>AGS</jats:italic> ) genes, designated as <jats:italic>AGS1</jats:italic> , <jats:italic>AGS2</jats:italic> , and <jats:italic>AGS3</jats:italic> , suggest that <jats:italic>AGS3</jats:italic> is expressed in vegetative and pathogenic hyphae, whereas expression of <jats:italic>AGS1</jats:italic> and <jats:italic>AGS2</jats:italic> was not, or barely, detectable. Targeted gene deletions yielded single and double deletion mutants, as well as triple mutants, which lacked the entire repertoire of α‐1,3‐glucan synthase genes. Conidia of mutants lacking <jats:italic>AGS3</jats:italic> developed multiple germ tubes, and vegetative hyphae had cell walls containing strongly reduced amounts of alkali‐soluble glucose, showed hyperbranching, reduced growth rates on all substrata tested, and hypersensitivity to the cell wall‐perturbing agents Caspofungin and Nikkomycin Z. Moreover, mutants lacking <jats:italic>AGS3</jats:italic> exhibited strong virulence defects and, intriguingly, biotrophic hyphae of these mutants that differentiated <jats:italic>in planta</jats:italic> were severely misshapen. Increased cell wall pore diameters, increased mobility of uncharged dextran‐FITC conjugates through cell walls of <jats:italic>AGS3</jats:italic> ‐deficient mutants and lack of PAMP‐triggered immune responses in maize leaves inoculated with these mutants suggest that α‐1,3‐glucan does not play a role in masking of fungal cell walls and immune evasion, but rather controls mobility of fungal cell wall‐modifying enzymes and cell wall integrity.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"1 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2026-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148922805","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":"Plasmodium Actin‐Like Proteins 3 and 5a Are Required for Subsequent Steps of Mosquito Infection","authors":"Caroline Busse, Yukino Kobayashi, Andrea Diers, Annika M. Binder, Friedrich Frischknecht, Ross G. Douglas","doi":"10.1111/mmi.70108","DOIUrl":"https://doi.org/10.1111/mmi.70108","url":null,"abstract":"Actin superfamily members are critical for the biology of eukaryotes and archaea. Actin‐related proteins (Arps) are a subgroup within the actin superfamily and play essential roles in trafficking, replication and motility. The genome of the malaria parasite <jats:italic>Plasmodium</jats:italic> contains a set of Arps unique to apicomplexans, termed actin‐like proteins (Alps). However, the importance and specific roles of many of these Alps in <jats:italic>Plasmodium</jats:italic> progression are not yet understood. Here, we determined the functional contribution of <jats:italic>Plasmodium berghei</jats:italic> Alp3 and Alp5a (recently relabelled as Arp3) by generation of knock‐out (KO) lines and their subsequent characterisation across different life cycle stages. Deletion of either Alp did not affect blood stage growth, gametogenesis and ookinete gliding motility. However, deletion of Alp5a led to smaller and fewer oocysts as well as severely impaired sporozoite formation. The Alp3KO line had highly reduced oocyst loads compared to wild‐type parasites. This striking decrease was due to impaired ookinete penetration of the mosquito midgut epithelium. Our study shows that both Alp3 and Alp5a are indispensable for <jats:italic>Plasmodium</jats:italic> transmission at different steps of initial mosquito infection, provides insights into the role of specific unique members of the actin superfamily during parasite progression and the requirements for efficient midgut penetration.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"24 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2026-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148768450","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":"Archaeal Cytoskeletal Protein CetZ1 Influences Assembly of the Motility Machinery","authors":"Hannah J. Brown, Md Imtiazul Islam, Juanfang Ruan, Matthew A. B. Baker, Solenne Ithurbide, Iain G. Duggin","doi":"10.1111/mmi.70109","DOIUrl":"https://doi.org/10.1111/mmi.70109","url":null,"abstract":"The archaeal tubulin‐like cytoskeletal protein CetZ1 is required for rod‐cell morphogenesis during the development of motility in <jats:styled-content style=\"fixed-case\"> <jats:italic>Haloferax volcanii</jats:italic> </jats:styled-content> . This is expected to improve swimming speed and directionality. Here, we found that deletion of <jats:italic>cetZ1</jats:italic> or expression of a GTPase‐defective mutant caused the expected defects in cell shape, and also resulted in a substantial defect in the assembly of the motility machinery, including the archaellum base marker protein ArlD1, the chemotaxis sensory array adapter CheW1, and signal transducer CheY. Interestingly, moderate overexpression of <jats:italic>cetZ1</jats:italic> (by 2–3 fold) reduced motility and the assembly and polar placement of the motility machinery without detectably affecting the rod shape of motile cells. We also investigated deletion of the conserved paralog <jats:italic>cetZ2</jats:italic> , which caused no detected defects in swimming or rod shape. However, overexpression of <jats:italic>cetZ2</jats:italic> caused mild hyper‐motility, whereas the <jats:italic>cetZ2</jats:italic> GTPase‐defective mutant reduced motility; these effects were dependent on the presence of <jats:italic>cetZ1</jats:italic> , suggesting that the altered <jats:italic>cetZ2</jats:italic> might interfere with CetZ1's role in motility. Finally, we saw that a functional CetZ1‐mTurquoise2 fusion strongly localized at the poles of mature motile cells, where it partially co‐localized with the motility machinery markers. Overall, our results suggest that roles of CetZ1 in cell shape or potentially the organisation and structure of the cell poles influence the polar assembly of the motility machinery.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"49 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2026-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148767567","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":"Characterization of Sec14 Domain–Containing Proteins in the Malaria Parasite Plasmodium falciparum","authors":"Florian Lauruol, Dominik Šťastný, J. Pedro Fernandez‐Murray, Christopher R. McMaster, Peter Griač, Dave Richard","doi":"10.1111/mmi.70107","DOIUrl":"https://doi.org/10.1111/mmi.70107","url":null,"abstract":"<jats:italic>Plasmodium falciparum</jats:italic> parasites cause the most virulent form of malaria, a disease that remains a major global health burden. The appearance of resistance to first line artemisinin‐based therapies emphasizes the need to identify new parasite vulnerabilities to develop new therapeutics. Phosphoinositides are central regulators of membrane identity, vesicular trafficking, and signaling, and their synthesis depends on tightly controlled phosphatidylinositol transfer by Sec14‐like phosphatidylinositol transfer proteins in many eukaryotes, yet their roles in <jats:italic>P. falciparum</jats:italic> remain poorly defined. Here, we analyzed six <jats:italic>P. falciparum</jats:italic> Sec14 domain–containing proteins: PfSec14‐1 (PF3D7_0626400), PfSec14‐2 (PF3D7_0629900), PfSec14‐3 (PF3D7_0717100), PfSec14‐4 (PF3D7_0920700), PfSec14‐5 (PF3D7_1007200), and PfSec14‐6 (PF3D7_1127600). Domain organization segregates these proteins into a BNIP‐2 and Cdc42GAP homology (BCH) subfamily (PfSec14‐3, PfSec14‐5) and a canonical Sec14 subfamily (PfSec14‐1, PfSec14‐2, PfSec14‐4, and PfSec14‐6). Yeast complementation assays showed that PfSec14‐1, PfSec14‐4, and PfSec14‐6 partially rescue growth of a temperature‐sensitive sec14 mutant, suggesting phosphatidylinositol and phosphatidylcholine transfer activity. Gene disruption revealed that PfSec14‐1 is important for asexual blood‐stage proliferation, whereas PfSec14‐2 is dispensable under standard culture conditions. In contrast, mislocalization of PfSec14‐2 and PfSec14‐4 using a knock‐sideways approach did not impair asexual growth. Subcellular localization indicates distinct distributions for PfSec14‐1, PfSec14‐2, and PfSec14‐4. Together, these findings reveal potential functional and spatial diversification of Sec14‐like phosphatidylinositol transfer proteins in <jats:italic>P. falciparum</jats:italic> .","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"93 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148715651","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":"Trypanosomal MICOS Is Assembled on Non‐Respiring Mitochondrial Crista Precursors and Associates With Two Integral Microproteins","authors":"Michala Boudová, Teresa Wagner, Tomáš Bílý, Martina Tesařová, Corinna Benz, Hassan Hashimi","doi":"10.1111/mmi.70105","DOIUrl":"https://doi.org/10.1111/mmi.70105","url":null,"abstract":"The mitochondrial contact site and cristae organizing system (MICOS) is a multiprotein complex that shapes crista junctions and maintains inner and outer membrane contacts. MICOS coordinates the assembly of electron transport chain complexes, a prerequisite for cellular respiration. Indeed, MICOS is lost in eukaryotes that dispensed with cellular respiration, suggesting that its assembly depends on the presence of an active respiratory chain. <jats:italic>Trypanosoma brucei</jats:italic> provides a unique system to test this hypothesis as its mitochondrion undergoes developmentally regulated remodeling. In the insect stage, the mitochondrion contains cristae with an active electron transport chain, whereas the mammalian bloodstream form possesses precursor cristae with stub‐like morphology that lack respiratory activity. MICOS has been characterized in the insect stage but remains unexamined in the bloodstream form. Here, we demonstrate that all MICOS subunits assemble onto precursor cristae, retaining conserved interactions with both outer and inner membrane protein machineries. This is somewhat unexpected given the co‐occurrence of MICOS with active cellular respiration in nature. Furthermore, we identify novel MICOS‐associated proteins that are dispensable for its stability, suggesting auxiliary rather than core roles in MICOS function. Together, our findings establish that MICOS assembly precedes cellular respiratory competence and expand its interaction landscape in trypanosomatids.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"46 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2026-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148687882","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":"Chain-Length Regulation by WzzE Is Necessary for, but Genetically Separable From, Cyclic Enterobacterial Common Antigen Synthesis.","authors":"Joseph F Carr, Yohannes H Rezenom, Jennifer S Rudolf, Daniel J Warzecha, Angela M Mitchell","doi":"10.1111/mmi.70088","DOIUrl":"10.1111/mmi.70088","url":null,"abstract":"<p><p>Enterobacterial common antigen (ECA) is a conserved glycan that supports intrinsic antibiotic resistance in Enterobacterales. ECA exists in outer membrane diacylglycerol-phosphate- and lipopolysaccharide-linked forms, and a cyclic periplasmic form (ECA_CYC). Intriguingly, ECA_CYC both affects the outer membrane permeability barrier and functions in regulation of diacylglycerol-phosphate-linked ECA. While the length of linear ECA polymers generated by WzyE is regulated by the co-polymerase WzzE, WzzE is also required for ECA_CYC biogenesis and no ECA_CYC is synthesized in its absence. To define WzzE functions necessary for ECA_CYC biosynthesis, we generated plasmid-borne wzzE mutants in Escherichia coli K-12 and quantified their effects on linear ECA regulation and ECA_CYC synthesis, determining that mutations disrupting linear ECA regulation in either transmembrane helix 2 or the periplasmic domain abolished ECA_CYC synthesis. Moreover, we identified two mutations residue F104 that differed in ECA_CYC abundance despite indistinguishable linear ECA regulation: wzzE_F104H caused an approximately 2-fold decrease in ECA_CYC abundance, whereas wzzE_F104Y retained wild-type abundance. Chromosomal wzzE mutants recapitulated this phenotype, demonstrating that these substitutions genetically uncouple levels of ECA_CYC synthesis from linear ECA regulation. Thus, although WzzE-mediated chain-length regulation is necessary for ECA_CYC biogenesis, it is not sufficient.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"190-207"},"PeriodicalIF":3.1,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13432762/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148278119","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":"To Move or Not to Move: When and How Bacteria Suppress Flagellar Motility.","authors":"Fatemeh Mohaghegh, Jacob Scadden, Matthew A B Baker","doi":"10.1111/mmi.70085","DOIUrl":"10.1111/mmi.70085","url":null,"abstract":"<p><p>Bacterial motility enables cells to migrate toward favourable environments and initiate surface colonisation. While motility can be lost through passive processes, such as shearing of filament, it frequently occurs as a tightly regulated response shaped by environmental and ecological conditions. Cessation of motility is often not only a passive consequence of environmental limitations but can also represent a tightly regulated and adaptive strategy that promotes bacterial survival, persistence and biofilm development. Stopping motility allows the bacterial cells to redirect energy and metabolic resources toward essential processes, including extracellular matrix production and stress tolerance. This transition facilitates niche adaptation through protective biofilm communities which enhance bacterial stability under environmental stressors such as nutrient limitation, antimicrobial agents and host immune defences. Collectively, motility cessation represents a regulated shift to protective and communal lifestyles, with implications for bacterial ecology and pathogenesis. Studies have shown that bacteria use diverse mechanisms and signals for flagellar suppression, highlighting the importance of motility regulation in bacterial adaptation to changing environments. In this review, we highlight various mechanisms governing motility cessation and discuss the functional and environmental reasons that suppress motility across bacterial species.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"173-189"},"PeriodicalIF":3.1,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13432727/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148252520","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":"The Role of torS and torT Transcription in Driving a Bet‐Hedging Strategy for Trimethylamine N ‐Oxide Reductase Expression in Escherichia coli","authors":"Erin L. Mettert, Jeffrey N. Carey, Wilma Ross, Mark Goulian, Patricia J. Kiley","doi":"10.1111/mmi.70103","DOIUrl":"https://doi.org/10.1111/mmi.70103","url":null,"abstract":"In <jats:styled-content style=\"fixed-case\"> <jats:italic>Escherichia coli</jats:italic> </jats:styled-content> , cell‐to‐cell variability in aerobic expression of trimethylamine <jats:italic>N</jats:italic> ‐oxide (TMAO) reductase serves as a bet‐hedging strategy, enabling a subset of cells to continue growing upon a shift to anaerobic conditions in the presence of TMAO. This variability has been attributed to the low abundance of TorS and TorT signaling proteins, which along with TorR, regulate transcription of <jats:italic>torCAD</jats:italic> encoding TMAO reductase. Here, we characterize the divergent promoters that drive expression of the bipartite sensor and kinase, TorT and TorS. In vitro transcription analysis identified two transcription start sites for <jats:italic>torS</jats:italic> and one start site for <jats:italic>torT</jats:italic> , all located in close proximity. Notably, the RNA polymerase‐σ <jats:sup>70</jats:sup> –10 element of the upstream <jats:italic>torS</jats:italic> promoter overlaps that of the <jats:italic>torT</jats:italic> promoter, defining it as a bidirectional promoter. We further demonstrate that these two promoters are subject to repression by the global regulator IscR, which binds to a site that partially overlaps the shared −10 elements. IscR binding antagonizes RNAP‐σ <jats:sup>70</jats:sup> binding, limiting transcription of both promoters and contributing to low <jats:italic>torS/torT</jats:italic> expression. Finally, we show that a single base substitution within the overlapping −10 elements increases <jats:italic>torS/torT</jats:italic> transcription by at least 4‐fold and abolishes cell‐to‐cell variability in <jats:italic>torCAD</jats:italic> expression, despite this promoter variant remaining sensitive to IscR‐mediated repression. Together, these findings indicate that promoter strength and transcriptional repression are critical components for regulated bet‐hedging, enabling <jats:styled-content style=\"fixed-case\"> <jats:italic>E. coli</jats:italic> </jats:styled-content> to optimize energy metabolism in response to fluctuations in oxygen availability and TMAO levels.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"22 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148650546","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":"Roles of PknB and CslA in Cell Wall Morphogenesis of Streptomyces.","authors":"Marta Derkacz, Andrew Watson, Akshada Gajbhiye, Michał Tracz, Dagmara Jakimowicz, Matthias Trost, Jeff Errington, Bernhard Kepplinger","doi":"10.1111/mmi.70086","DOIUrl":"10.1111/mmi.70086","url":null,"abstract":"<p><p>The bacterial cell wall is essential for maintaining cellular integrity and defining the mode of growth, with different species adopting distinct strategies for cell wall synthesis and remodelling. Streptomyces are filamentous bacteria predominantly found in soil and renowned for producing specialised metabolites, including antibiotics. They grow through tip extension and branching hyphal filaments, forming a multicellular mycelium. New branches are established by forming a new growth zone on the lateral cell wall. Proteins involved in this process are organised into complexes called polarisomes, with DivIVA being the most well-characterised component. To investigate the tip growth requirements in Streptomyces albus we developed a genetic screen utilising toxic DivIVA overproduction and searched for suppressors of its lethality, reasoning that such suppressors would likely encode components functionally linked to DivIVA or the tip growth machinery. Among the identified genes was pknB, encoding a serine/threonine protein kinase implicated in the regulation of cell growth and morphogenesis. We confirmed that deletion of pknB restored the growth phenotype of S. albus following DivIVA overproduction. The phosphoproteome analysis revealed that the absence of PknB alters the phosphorylation state of CslA, a cellulose synthase that synthesizes a beta-glucan (cellulose) polymer. We demonstrate that a phosphoablative mutant of CslA impairs beta-glucan synthesis and causes hypersensitivity to lysozyme. Overproduction of CslA restored colony growth defects arising from DivIVA-induced hyperbranching, without however suppressing the hyperbranching phenotype. These findings collectively identify PknB-dependent phosphorylation of CslA as a central regulatory point in Streptomyces cell envelope construction, revealing how modulation of beta-glucan synthesis can mitigate the cellular consequences of DivIVA dysregulation.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"161-172"},"PeriodicalIF":3.1,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13432765/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148211976","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}