CcpC, a novel regulator of the LysR family required for glucose repression of the citB gene in Bacillus subtilis

Cécile Jourlin-Castelli, Nagraj Mani, Michiko M. Nakano, Abraham L. Sonenshein

Research output: Contribution to journalArticle

77 Scopus citations

Abstract

Synergistic carbon catabolite repression of the Bacillus subtilis aconitase (citB) gene by glucose and a source of 2-ketoglutarate is dependent on DNA sequences located upstream of the gene. Mutations in a dyad symmetry element centered at position -66 and in a repeat of the downstream arm of the dyad symmetry at position -27 cause derepressed citB expression. In this work, a protein able to bind to a DNA fragment containing these elements was purified and identified. This protein, named CcpC (Catabolite control protein C), shares sequence similarity with members of the LysR family of transcriptional regulators. In addition to binding to the citB promoter, CcpC bound to the promoter of the citZ gene, which encodes the cell's major citrate synthase and is subject to carbon catabolite repression. In a ccpC null mutant, expression of both citB and citZ was derepressed in glucose-glutamine minimal medium, indicating that CcpC is a negative regulator of citB and citZ gene expression. DNase I footprinting experiments showed that CcpC binds to two sites within the citB promoter region, corresponding to the dyad symmetry and -27 elements. In the presence of citrate, a putative inducer, only the dyad symmetry element was fully protected by CcpC. When the dyad symmetry element was mutated, CcpC was no longer able to bind to either the dyad symmetry or -27 elements. Repression of citB and citZ gene expression during anaerobiosis also proved to be mediated by CcpC. (C) 2000 Academic Press.

Original languageEnglish (US)
Pages (from-to)865-878
Number of pages14
JournalJournal of molecular biology
Volume295
Issue number4
DOIs
StatePublished - Jan 28 2000

Keywords

  • Aconitase
  • Bacillus subtilis
  • Catabolite repression
  • LysR family

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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