title: Requirement for two copies of RNA polymerase alpha subunit C-terminal domain for synergistic transcription activation at complex bacterial promoters.
abstract: Transcription activation by the Escherichia coli cyclic AMP receptor protein (CRP) at different promoters has been studied using RNA polymerase holoenzyme derivatives containing two full-length alpha subunits, or containing one full-length alpha subunit and one truncated alpha subunit lacking the alpha C-terminal domain (alpha CTD). At a promoter having a single DNA site for CRP, activation requires only one full-length alpha subunit. Likewise, at a promoter having a single DNA site for CRP and one adjacent UP-element subsite (high-affinity DNA site for alpha CTD), activation requires only one full-length alpha subunit. In contrast, at promoters having two DNA sites for CRP, or one DNA site for CRP and two UP-element subsites, activation requires two full-length alpha subunits. We conclude that a single copy of alpha CTD is sufficient to interact with one CRP molecule and one adjacent UP-element subsite, but two copies of alpha CTD are required to interact with two CRP molecules or with one CRP molecule and two UP-element subsites.
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002373:Cyclic AMP Receptor Protein / Q000378:metabolism*; D004269:DNA, Bacterial; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D015533:Transcriptional Activation
chemical_list: D002373:Cyclic AMP Receptor Protein; D004269:DNA, Bacterial; D012321:DNA-Directed RNA Polymerases; C113275:RNA polymerase alpha subunit