BglJ-RcsB heterodimers relieve repression of the Escherichia coli bgl operon by H-NS.

TitleBglJ-RcsB heterodimers relieve repression of the Escherichia coli bgl operon by H-NS.
Publication TypeJournal Article
Year of Publication2010
AuthorsVenkatesh, RG, Kembou Koungni, FC, Paukner, A, Stratmann, T, Blissenbach, B, Schnetz, K
JournalJ Bacteriol
Date Published2010 Dec
KeywordsBase Sequence, Chromosome Mapping, Chromosomes, Bacterial, Escherichia coli, Escherichia coli Proteins, Fimbriae Proteins, Gene Expression Regulation, Bacterial, Molecular Sequence Data, Operon, Protein Binding, Trans-Activators, Transcription Factors

RcsB is the response regulator of the complex Rcs two-component system, which senses perturbations in the outer membrane and peptidoglycan layer. BglJ is a transcriptional regulator whose constitutive expression causes activation of the H-NS- and StpA-repressed bgl (aryl-β,D-glucoside) operon in Escherichia coli. RcsB and BglJ both belong to the LuxR-type family of transcriptional regulators with a characteristic C-terminal DNA-binding domain. Here, we show that BglJ and RcsB interact and form heterodimers that presumably bind upstream of the bgl promoter, as suggested by mutation of a sequence motif related to the consensus sequence for RcsA-RcsB heterodimers. Heterodimerization of BglJ-RcsB and relief of H-NS-mediated repression of bgl by BglJ-RcsB are apparently independent of RcsB phosphorylation. In addition, we show that LeuO, a pleiotropic LysR-type transcriptional regulator, likewise binds to the bgl upstream regulatory region and relieves repression of bgl independently of BglJ-RcsB. Thus, LeuO can affect bgl directly, as shown here, and indirectly by activating the H-NS-repressed yjjQ-bglJ operon, as shown previously. Taken together, heterodimer formation of RcsB and BglJ expands the role of the Rcs two-component system and the network of regulators affecting the bgl promoter.

Alternate JournalJ. Bacteriol.