Transcription activation by the siderophore sensor Btr is mediated by ligand-dependent stimulation of promoter clearance.

ABSTRACT: Bacterial transcription factors often function as DNA-binding proteins that selectively activate or repress promoters, although the biochemical mechanisms vary. In most well-understood examples, activators function by either increasing the affinity of RNA polymerase (RNAP) for the target promoter, or by increasing the isomerization of the initial closed complex to the open complex. We report that Bacillus subtilis Btr, a member of the AraC family of activators, functions principally as a ligand-dependent activator of promoter clearance. In the presence of its co-activator, the siderophore bacillibactin (BB), the Btr:BB complex enhances productive transcription, while having only modest effects on either RNAP promoter association or the production of abortive transcripts. Btr binds to two d

SUBMITTER: Gaballa A 

PROVIDER: S-EPMC3333878 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature