The functional subunit of a dimeric transcription activator protein depends on promoter architecture.
In Class I CAP-dependent promoters, the DNA site for CAP is located upstream of the DNA site for RNA polymerase. In Class II CAP-dependent promoters, the DNA site for CAP overlaps the DNA site for RNA polymerase, replacing the -35 site. We have used an 'oriented heterodimers' approach to identify the functional subunit of CAP at two Class I promoters having different distances between the DNA sites for CAP and RNA polymerase [CC(-61.5) and CC(-72.5)] and at one Class II promoter [CC(-41.5)]. Our results indicate that transcription activation at Class I promoters, irrespective of the distance between the DNA sites for CAP and RNA polymerase, requires the activating region of the promoter-proximal subunit of CAP. In striking contrast, our results indicate that transcription activation at Class II promoters requires the activating region of the promoter-distal subunit of CAP.
Zhou
Y
Y
Department of Chemistry, Rutgers University, New Brunswick, NJ 08855.
Pendergrast
P S
PS
Bell
A
A
Williams
R
R
Busby
S
S
Ebright
R H
RH
D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology; D001483:Base Sequence; D001704:Biopolymers; D002373:Cyclic AMP Receptor Protein / Q000737:chemistry* / Q000502:physiology*; D004269:DNA, Bacterial / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000502:physiology*; D012321:DNA-Directed RNA Polymerases / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000502:physiology*
D001426:Bacterial Proteins; D001704:Biopolymers; D002373:Cyclic AMP Receptor Protein; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases