Role of DNA methylation at GATC sites in the dnaA promoter, dnaAp2

J Mol Microbiol Biotechnol. 2000 Jul;2(3):301-10.

Abstract

DnaA protein is required for the initiation of DNA replication at the bacterial chromosomal origin, oriC, and at the origins of many plasmids. The concentration of DnaA protein is an important factor in determining when initiation occurs during the cell cycle. Methylation of GATC sites in the dnaAp2 promoter, two of which are in the -35 and -10 sequences, has been predicted to play an important role in regulating dnaA gene expression during the cell cycle because the promoter is sequestered from methylation immediately following replication. Mutations that eliminate these two GATC sites but do not substantially change the activity of the promoter were introduced into a reporter gene fusion and into the chromosome. The chromosomal mutants are able to initiate DNA replication synchronously at both moderately slow and fast growth rates, demonstrating that GATC methylation at these two sites is not directly involved in providing the necessary amount of DnaA for precise timing of initiation during the cell cycle. Either sequestration does not involve these GATC sites, or cell cycle control of DnaA expression is not required to supply the concentration necessary for correct timing of initiation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism*
  • Chromosomes, Bacterial
  • DNA Methylation*
  • DNA Replication
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism*
  • Escherichia coli / genetics
  • Hexosyltransferases / genetics
  • Hexosyltransferases / metabolism
  • Mutation
  • Operon
  • Promoter Regions, Genetic
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism

Substances

  • Bacterial Proteins
  • DNA-Binding Proteins
  • DnaA protein, Bacteria
  • Recombinant Fusion Proteins
  • Hexosyltransferases
  • levansucrase