DnaB, DnaD and DnaI proteins are components of the Bacillus subtilis replication restart primosome

Mol Microbiol. 2001 Oct;42(1):245-55. doi: 10.1046/j.1365-2958.2001.02631.x.


Phenotypes of Bacillus subtilis priA mutants suggest that they are deficient in the restart of stalled chromosomal replication forks. The presumed activity of PriA in the restart process is to promote the assembly of a multiprotein complex, the primosome, which functions to recruit the replication fork helicase onto the DNA. We have proposed previously that three proteins involved in the initiation of replication at oriC in B. subtilis, DnaB, DnaD and DnaI, are components of the PriA primosome in this bacterium. However, the involvement of these proteins in replication restart has not yet been studied. Here, we describe dnaB mutations that suppress the phenotypes of B. subtilis priA mutants. In a representative mutant, the DnaC helicase is loaded onto single-stranded DNA in a PriA-independent, DnaD- and DnaI-dependent manner. These observations confirm that DnaB, DnaD and DnaI are primosomal proteins in B. subtilis. Moreover, their involvement in the suppression of priA phenotypes shows that they participate in replication fork restart in B. subtilis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus subtilis / genetics
  • Bacillus subtilis / metabolism*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • DNA Helicases / genetics
  • DNA Helicases / metabolism*
  • DNA Primase / metabolism
  • DNA Replication*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • DnaB Helicases
  • Escherichia coli Proteins*
  • Mutation
  • Replication Protein A
  • Suppression, Genetic


  • Bacterial Proteins
  • DNA-Binding Proteins
  • DnaC protein, E coli
  • DnaD protein, Bacillus subtilis
  • Escherichia coli Proteins
  • Replication Protein A
  • DNA Primase
  • DNA Helicases
  • DnaB Helicases