title: Effect oftcdRMutation on Sporulation in the EpidemicClostridium difficileStrain R20291.
abstract: Clostridium difficileis an important nosocomial pathogen and the leading cause of hospital-acquired diarrhea. Antibiotic use is the primary risk factor for the development ofC. difficile-associated disease because it disrupts normally protective gut flora and enablesC. difficileto colonize the colon.C. difficiledamages host tissue by secreting toxins and disseminates by forming spores. The toxin-encoding genes,tcdAandtcdB, are part of a pathogenicity locus, which also includes thetcdRgene that codes for TcdR, an alternate sigma factor that initiates transcription oftcdAandtcdBgenes. We created atcdRmutant in epidemic-typeC. difficilestrain R20291 in an attempt to identify the global role oftcdR. A site-directed mutation intcdRaffected both toxin production and sporulation inC. difficileR20291. Spores of thetcdRmutant were more heat sensitive than the wild type (WT). Nearly 3-fold more taurocholate was needed to germinate spores from thetcdRmutant than to germinate the spores prepared from the WT strain. Transmission electron microscopic analysis of the spores also revealed a weakly assembled exosporium on thetcdRmutant spores. Accordingly, comparative transcriptome analysis showed many differentially expressed sporulation genes in thetcdRmutant compared to the WT strain. These data suggest that regulatory networks of toxin production and sporulation inC. difficilestrain R20291are linked with each other.IMPORTANCEC. difficileinfects thousands of hospitalized patients every year, causing significant morbidity and mortality.C. difficilespores play a pivotal role in the transmission of the pathogen in the hospital environment. During infection, the spores germinate, and the vegetative bacterial cells produce toxins that damage host tissue. Thus, sporulation and toxin production are two important traits ofC. difficile. In this study, we showed that a mutation intcdR, the toxin gene regulator, affects both toxin production and sporulation in epidemic-typeC. difficilestrain R20291.
authors.affiliation: Division of Biology, Kansas State University, Manhattan, Kansas, USA.
authors.forename: Brintha P
authors.initials: BP
authors.lastname: Girinathan
authors.affiliation: Department of Microbiology, Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Monot
authors.affiliation: Division of Biology, Kansas State University, Manhattan, Kansas, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Boyle
authors.affiliation: Department of Biology, Texas A&M University, College Station, Texas, USA.
authors.forename: Kathleen N
authors.initials: KN
authors.lastname: McAllister
authors.affiliation: Department of Biology, Texas A&M University, College Station, Texas, USA.
authors.forename: Joseph A
authors.identifier: 0000-0001-7822-2656
authors.initials: JA
authors.lastname: Sorg
authors.affiliation: Department of Microbiology, Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Dupuy
authors.affiliation: Division of Biology, Kansas State University, Manhattan, Kansas, USA.
authors.forename: Revathi
authors.initials: R
authors.lastname: Govind
keywords: Clostridium difficile; sporulation; toxin gene regulation