Regulatory cross-talk links Vibrio cholerae chromosome II replication and segregation

PLoS Genet. 2011 Jul;7(7):e1002189. doi: 10.1371/journal.pgen.1002189. Epub 2011 Jul 21.

Abstract

There is little knowledge of factors and mechanisms for coordinating bacterial chromosome replication and segregation. Previous studies have revealed that genes (and their products) that surround the origin of replication (oriCII) of Vibrio cholerae chromosome II (chrII) are critical for controlling the replication and segregation of this chromosome. rctB, which flanks one side of oriCII, encodes a protein that initiates chrII replication; rctA, which flanks the other side of oriCII, inhibits rctB activity. The chrII parAB2 operon, which is essential for chrII partitioning, is located immediately downstream of rctA. Here, we explored how rctA exerts negative control over chrII replication. Our observations suggest that RctB has at least two DNA binding domains--one for binding to oriCII and initiating replication and the other for binding to rctA and thereby inhibiting RctB's ability to initiate replication. Notably, the inhibitory effect of rctA could be alleviated by binding of ParB2 to a centromere-like parS site within rctA. Furthermore, by binding to rctA, ParB2 and RctB inversely regulate expression of the parAB2 genes. Together, our findings suggest that fluctuations in binding of the partitioning protein ParB2 and the chrII initiator RctB to rctA underlie a regulatory network controlling both oriCII firing and the production of the essential chrII partitioning proteins. Thus, by binding both RctB and ParB2, rctA serves as a nexus for regulatory cross-talk coordinating chrII replication and segregation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Binding Sites / genetics
  • Chromosomes, Bacterial / genetics*
  • Chromosomes, Bacterial / metabolism
  • DNA Replication / genetics
  • DNA, Bacterial / genetics
  • DNA, Bacterial / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Electrophoretic Mobility Shift Assay
  • Gene Expression Regulation, Bacterial*
  • Gene Regulatory Networks
  • Operon
  • Plasmids / genetics
  • Plasmids / metabolism
  • Promoter Regions, Genetic / genetics
  • Protein Binding
  • Replication Origin / genetics
  • Vibrio cholerae / genetics*
  • Vibrio cholerae / metabolism

Substances

  • Bacterial Proteins
  • DNA, Bacterial
  • DNA-Binding Proteins
  • chromosome partition proteins, bacterial
  • Adenosine Triphosphatases