We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
A conserved region in the σ54-dependent activator DctD is involved in both binding to RNA polymerase and coupling ATP hydrolysis to activation.
- Authors
Ying-Kai Wang; Lee, Joon H.; Brewer, John M.; Hoover, Timothy R.
- Abstract
<em>Rhizobium melioti</em> DctD activates transcription from the <em>dctA</em> promoter by catalysing the isomerization of closed complexes between σ54-RNA polymerase holoenzyme and the promoter to open complexes. DctD must make productive contact with σ54-holoenzyme and hydrolyse ATP to catalyse this isomerization. To define further the activation process, we sought to isolate mutants of DctD that had reduced affinities for σ54-holoenzyme. Mutagenesis was confined to the well-conserved C3 region of the protein, which is required for coupling ATP hydrolysis to open complex formation in σ54-dependent activators. Mutant forms of DctD that failed to activate transcription and had substitutions in the C-terminal half of the C3 region were efficiently cross-linked to σ54 and the β-subunit of RNA polymerase, suggesting that they bound normally to σ54-holoenzyme. In contrast, some mutant forms of DctD with amino acid substitutions in the N-terminal half of the C3 region had reduced affinities for σ54 and the β-subunit in the cross-linking assay. These data suggest that the N-terminal half of the C3 region of DctD contains a site that may contact σ54-holoenzyme during open complex formation.
- Subjects
RHIZOBIUM meliloti; PROMOTERS (Genetics); GENETIC transcription; MUTAGENESIS; ADENOSINE triphosphate; GENETIC mutation
- Publication
Molecular Microbiology, 1997, Vol 26, Issue 2, p373
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1046/j.1365-2958.1997.5851955.x