Identification of the site-specific DNA invertase responsible for the phase variation of SusC/SusD family outer membrane proteins in Bacteroides fragilis

J Bacteriol. 2009 Oct;191(19):6003-11. doi: 10.1128/JB.00687-09. Epub 2009 Jul 31.

Abstract

The human gut microbe Bacteroides fragilis can alter the expression of its surface molecules, such as capsular polysaccharides and SusC/SusD family outer membrane proteins, through reversible DNA inversions. We demonstrate here that DNA inversions at 12 invertible regions, including three gene clusters for SusC/SusD family proteins, were controlled by a single tyrosine site-specific recombinase (Tsr0667) encoded by BF0667 in B. fragilis strain YCH46. Genetic disruption of BF0667 diminished or attenuated shufflon-type DNA inversions at all three susC/susD genes clusters, as well as simple DNA inversions at nine other loci, most of which colocalized with susC/susD family genes. The inverted repeat sequences found within the Tsr0667-regulated invertible regions shared the consensus motif sequence AGTYYYN(4)GDACT. Tsr0667 specifically mediated the DNA inversions of 10 of the 12 regions, even under an Escherichia coli background when the invertible regions were exposed to BF0667 in E. coli cells. Thus, Tsr0667 is an additional globally acting DNA invertase in B. fragilis, which probably involves the selective expression of SusC/SusD family outer membrane proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Outer Membrane Proteins / metabolism*
  • Bacteroides fragilis / enzymology*
  • Bacteroides fragilis / genetics*
  • Base Sequence
  • DNA Nucleotidyltransferases / genetics
  • DNA Nucleotidyltransferases / metabolism*
  • DNA, Bacterial / genetics
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Inverted Repeat Sequences / genetics*
  • Molecular Sequence Data
  • Multigene Family / genetics
  • Polymerase Chain Reaction
  • Recombination, Genetic / genetics*
  • Sequence Homology, Nucleic Acid

Substances

  • Bacterial Outer Membrane Proteins
  • DNA, Bacterial
  • DNA Nucleotidyltransferases
  • Site-specific recombinase