Escherichia coli catabolite gene activator protein mutants defective in positive control of lac operon transcription.
We isolated three Escherichia coli catabolite gene activator protein mutants that are defective in the positive control of transcription initiation from the lac operon promoter region yet retain negative control of transcription from other promoters. One mutant has a substitution of valine for glutamate at residue 72, which lies in the cyclic AMP binding domain and contacts cyclic AMP. The other two mutants have substitutions of asparagine and cysteine for glycine 162, which lies in a surface-exposed turn of the DNA-binding domain. Surprisingly, although all three mutants can repress the lacP2/P3 promoters through the catabolite gene activator protein target site of lac, none displays strong dominance over the ability of wild-type catabolite gene activator protein to stimulate the lacP1 promoter.
Eschenlauer
A C
AC
Department of Biochemistry, University of Wisconsin, Madison 53706.
Reznikoff
W S
WS
D001483:Base Sequence; D000242:Cyclic AMP / Q000378:metabolism; D002373:Cyclic AMP Receptor Protein / Q000235:genetics*; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics*; D007763:Lac Operon; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics; D014158:Transcription, Genetic
D002373:Cyclic AMP Receptor Protein; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D000242:Cyclic AMP