Redox-sensitive transcriptional control by a thiol/disulphide switch in the global regulator, Spx

Shunji Nakano, Kyle N. Erwin, Martina Ralle, Peter Zuber

Research output: Contribution to journalArticle

111 Scopus citations

Abstract

The Spx protein is indispensable for survival of Bacillus subtilis under disulphide stress. Its interaction with the α-subunit of RNA polymerase is required for transcriptional induction of genes that function in thiol homeostasis, such as thioredoxin (trxA) and thioredoxin reductase (trxB). The N-terminal end of Spx contains a Cys-X-X-Cys (CXXC) motif, which is a likely target for redox-sensitive control. We show here that Spx directly activates trxA and -B transcription by interacting with the RMA polymerase α-subunit, but it does so only under an oxidized condition. The transcriptional activation by Spx requires formation of an intramolecular disulphide bond between two cysteine residues that reside in the CXXC motif. The mechanism of Spx-dependent transcriptional activation is unique in that it does not involve initial Spx-DNA interaction.

Original languageEnglish (US)
Pages (from-to)498-510
Number of pages13
JournalMolecular Microbiology
Volume55
Issue number2
DOIs
StatePublished - Jan 1 2005

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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