Role of the biofilm master regulator CsgD in cross-regulation between biofilm formation and flagellar synthesis

J Bacteriol. 2011 May;193(10):2587-97. doi: 10.1128/JB.01468-10. Epub 2011 Mar 18.

Abstract

CsgD, the master regulator of biofilm formation, activates the synthesis of curli fimbriae and extracellular polysaccharides in Escherichia coli. To obtain insights into its regulatory role, we have identified a total of 20 novel regulation target genes on the E. coli genome by using chromatin immunoprecipitation (ChIP)-on-chip analysis with a high-density DNA microarray. By DNase I footprinting, the consensus CsgD-binding sequence predicted from a total of 18 target sites was found to include AAAAGNG(N(2))AAAWW. After a promoter-lacZ fusion assay, the CsgD targets were classified into two groups: group I genes, such as fliE and yhbT, are repressed by CsgD, while group II genes, including yccT and adrA, are activated by CsgD. The fliE and fliEFGH operons for flagellum formation are directly repressed by CsgD, while CsgD activates the adrA gene, which encodes an enzyme for synthesis of cyclic di-GMP, a bacterial second messenger, which in turn inhibits flagellum production and rotation. Taking these findings together, we propose that the cell motility for planktonic growth is repressed by CsgD, thereby promoting the switch to biofilm formation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Artificial Gene Fusion
  • Bacterial Proteins / biosynthesis*
  • Binding Sites
  • Biofilms / growth & development*
  • Chromatin Immunoprecipitation
  • Consensus Sequence
  • DNA Footprinting
  • DNA, Bacterial / genetics
  • DNA, Bacterial / metabolism
  • Escherichia coli / genetics
  • Escherichia coli / physiology*
  • Escherichia coli Proteins / metabolism*
  • Flagella / metabolism
  • Gene Expression Regulation, Bacterial*
  • Genes, Reporter
  • Oligonucleotide Array Sequence Analysis / methods
  • Promoter Regions, Genetic
  • Protein Binding
  • Regulon
  • Trans-Activators / metabolism*
  • beta-Galactosidase / genetics
  • beta-Galactosidase / metabolism

Substances

  • Bacterial Proteins
  • CsgD protein, E coli
  • DNA, Bacterial
  • Escherichia coli Proteins
  • Trans-Activators
  • Crl protein, Bacteria
  • beta-Galactosidase