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The SKHR motif is required for biological function of the VirR response regulator from Clostridium perfringens

Sheena McGowan1, Jennifer R O'Connor, Jackie K Cheung

  • 1Bacterial Pathogenesis Research Group, Department of Microbiology, Monash University, Victoria 3800, Australia.

Journal of Bacteriology
|October 4, 2003
PubMed

Insights

The VirR response regulator controls toxin genes in Clostridium perfringens. Key amino acids, including Met-172 and the SKHR motif in VirRc, are essential for its DNA binding and biological function.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • The human pathogen Clostridium perfringens relies on toxin production for virulence.
  • The response regulator VirR, alongside its sensor histidine kinase VirS, governs the expression of these critical toxin genes.
  • The C-terminal domain of VirR (VirRc) possesses a conserved FxRxHrS motif crucial for DNA binding.

Purpose of the Study:

  • To investigate the functional role of the VirRc domain in DNA binding.
  • To identify specific amino acid residues essential for VirR's biological activity and DNA binding efficiency.
  • To elucidate the structure-function relationship of VirR in Clostridium perfringens.

Main Methods:

  • Cloning and purification of the VirRc domain.
  • In vivo and in vitro functional assays.
  • Random and site-directed mutagenesis to analyze protein function and DNA binding.
  • Analysis of mutated protein binding affinity to target DNA.

Main Results:

  • VirRc was confirmed as an independent DNA binding domain.
  • Mutagenesis identified Met-172 as a critical residue for VirR function.
  • The SKHR motif (amino acids 216-219) was also found to be essential for biological activity.
  • Mutated proteins exhibited reduced DNA binding efficiency compared to the wild-type.

Conclusions:

  • Specific amino acid residues, including Met-172 and the SKHR motif within VirRc, are indispensable for VirR's DNA binding capability and regulatory function.
  • These findings provide insights into the molecular mechanisms of toxin gene regulation in Clostridium perfringens.
  • Understanding these regulatory elements can inform strategies to control pathogen virulence.

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