A novel regulator controls Clostridium difficile sporulation, motility and toxin production

Mol Microbiol. 2016 Jun;100(6):954-71. doi: 10.1111/mmi.13361. Epub 2016 Mar 22.


Clostridium difficile is an anaerobic pathogen that forms spores which promote survival in the environment and transmission to new hosts. The regulatory pathways by which C. difficile initiates spore formation are poorly understood. We identified two factors with limited similarity to the Rap sporulation proteins of other spore-forming bacteria. In this study, we show that disruption of the gene CD3668 reduces sporulation and increases toxin production and motility. This mutant was more virulent and exhibited increased toxin gene expression in the hamster model of infection. Based on these phenotypes, we have renamed this locus rstA, for regulator of sporulation and toxins. Our data demonstrate that RstA is a bifunctional protein that upregulates sporulation through an unidentified pathway and represses motility and toxin production by influencing sigD transcription. Conserved RstA orthologs are present in other pathogenic and industrial Clostridium species and may represent a key regulatory protein controlling clostridial sporulation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Bacterial Toxins / biosynthesis
  • Bacterial Toxins / genetics
  • Clostridium difficile / genetics
  • Clostridium difficile / growth & development
  • Clostridium difficile / metabolism
  • Clostridium difficile / physiology*
  • Disease Models, Animal
  • Enterocolitis, Pseudomembranous / microbiology
  • Female
  • Gene Expression Regulation, Bacterial
  • Mesocricetus
  • Spores, Bacterial
  • Transcription Factors / metabolism


  • Bacterial Toxins
  • Transcription Factors