Asymmetric arrangement of two alpha subunits within Escherichia coli RNA polymerase. Involvement of one alpha subunit in contact with cAMP receptor protein.
Class I transcription factors of Escherichia coli have been proposed to make contact with contact site I on the alpha subunit, C-terminal region of RNA polymerase with the subunit composition of alpha 2 beta beta ' sigma. Both a reconstituted mutant holoenzyme containing two C-terminally truncated alpha-235 subunits and a hybrid enzyme containing one wild-type alpha (alpha-329) and one C-terminal truncated alpha (alpha-235) subunit were found to be as active in transcription from factor-independent simple promoters as the wild-type holoenzyme. The mutant enzyme was, however, inactive in cAMP receptor protein (CRP)-dependent transcription from lacP1 promoter, but the hybrid enzyme was about 50% as active in lacP1 transcription as the wild-type enzyme. The results indicate that only one specific alpha subunit makes contact with CRP.
Zou
C
C
Department of Molecular Genetics, National Institute of Genetics, Mishima, Shizuoka, Japan.
Fujita
N
N
Ishihama
A
A
D012321:DNA-Directed RNA Polymerases / Q000737:chemistry* / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D046911:Macromolecular Substances; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D013329:Structure-Activity Relationship; D013698:Templates, Genetic; D014158:Transcription, Genetic
D046911:Macromolecular Substances; D012321:DNA-Directed RNA Polymerases