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Clostridioides difficile (C. difficile) RT027 strains cause infections that vary in severity from asymptomatic to lethal, but the molecular basis for this variability is poorly understood. Through comparative analyses of RT027 clinical isolates, we determine that isolates that exhibit greater heterogeneity in their flagellar gene expression exhibit greater virulence in vivo. C. difficile flagellar genes are phase-variably expressed due to the site-specific inversion of the flgB 5' UTR region, which reversibly generates ON vs. OFF orientations for the flagellar switch. We find that longer inverted repeat (IR) sequences in this switch region correlate with greater disease severity, with RT027 strains carrying 6A/6T IR sequences exhibiting greater phenotypic heterogeneity in flagellar gene expression (60%-75% ON) and causing more severe disease than those with shorter IRs (>99% ON or OFF). Our results reveal that phenotypic heterogeneity in flagellar gene expression may contribute to the variable disease severity observed in C. difficile patients.
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http://dx.doi.org/10.1016/j.celrep.2025.115830 | DOI Listing |
mBio
September 2025
School of Biological Sciences, University of Auckland, Auckland, New Zealand.
The rotation of the bacterial flagellum is powered by the MotAB stator complex, which converts ion flux into torque. Despite its central role in flagellar function, the evolutionary origin and structural diversity of this system remain poorly understood. Here, we present the first comprehensive phylogenetic and structural characterization of MotAB and its closest non-flagellar homologs.
View Article and Find Full Text PDFAsian J Androl
September 2025
Reproductive Medicine Center, Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei 230032, China.
Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder characterized by impaired motility of cilia and flagella. Mutations in cilia- and flagella-associated protein 300 (CFAP300) are associated with human PCD and male infertility; however, the underlying pathogenic mechanisms remain poorly understood. In a consanguineous Chinese family, we identified a homozygous CFAP300 loss-of-function variant (c.
View Article and Find Full Text PDFbioRxiv
July 2025
Department of Molecular Genetics & Cell Biology, University of Chicago, Chicago, IL, USA.
Evolutionary constraints governing flagellar number in bacterial pathogens remain poorly understood. While related species are hyperflagellated, maintains strict monoflagellation through the FleQ-FleN regulatory circuit. Here, we demonstrate that FleN dosage is essential for maintaining monoflagellation and bacterial fitness.
View Article and Find Full Text PDFFront Med (Lausanne)
June 2025
McKusick-Zhang Center for Genetic Medicine, State Key Laboratory for Complex Severe and Rare Diseases, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China.
Background: Primary ciliary dyskinesia (PCD) is a genetically heterogeneous ciliopathy caused by structural and functional abnormalities of motile cilia. Although over 50 PCD-associated genes have been reported, the genetic spectrum remains incomplete. , a gene linked to multiple morphological abnormalities of the flagella, has recently been implicated in PCD; however, further case studies are needed to strengthen this conclusion.
View Article and Find Full Text PDFCell Rep
June 2025
Department of Medicine, University of Chicago, Chicago, IL 60637, USA; Duchossois Family Institute, University of Chicago, Chicago, IL 60637, USA; Department of Molecular Biology and Microbiology, Tufts University, Boston, MA 02111, USA. Electronic address:
Clostridioides difficile (C. difficile) RT027 strains cause infections that vary in severity from asymptomatic to lethal, but the molecular basis for this variability is poorly understood. Through comparative analyses of RT027 clinical isolates, we determine that isolates that exhibit greater heterogeneity in their flagellar gene expression exhibit greater virulence in vivo.
View Article and Find Full Text PDF