Location, structure, and function of the target of a transcriptional activator protein.
We have isolated and characterized single-amino-acid substitution mutants of RNA polymerase alpha subunit defective in CAP-dependent transcription at the lac promoter but not defective in CAP-independent transcription. Our results establish that (1) amino acids 258-265 of alpha constitute an "activation target" essential for CAP-dependent transcription at the lac promoter but not essential for CAP-independent transcription, (2) amino acid 261 is the most critical amino acid of the activation target, (3) amino acid 261 is distinct from the determinants for alpha-DNA interaction, and (4) the activation target may fold as a surface amphipathic alpha-helix. We propose a model for transcriptional activation at the lac promoter that integrates these and other recent results regarding transcriptional activation and RNA polymerase structure and function.
Tang
H
H
Department of Chemistry, Rutgers University, New Brunswick, New Jersey 08855.
Severinov
K
K
Goldfarb
A
A
Fenyo
D
D
Chait
B
B
Ebright
R H
RH
D000595:Amino Acid Sequence; D001483:Base Sequence; D002373:Cyclic AMP Receptor Protein / Q000378:metabolism*; D017931:DNA Primers; D004269:DNA, Bacterial / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000096:biosynthesis / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
D002373:Cyclic AMP Receptor Protein; D017931:DNA Primers; D004269:DNA, Bacterial; D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D012321:DNA-Directed RNA Polymerases