Roles for GcvA-binding sites 3 and 2 and the Lrp-binding region in gcvT::lacZ expression in Escherichia coli.
GcvA and Lrp are both necessary for activation of the gcv operon. The upstream GcvA-binding sites 3 and 2 were separated from the Lrp-binding region and the rest of the gcv control region. Moving these sites by 1 or 2 helical turns of DNA further from the gcv promoter reduces, but does not eliminate, either GcvA-mediated activation or repression of a gcvT::lacZ gene fusion. However, moving these sites by 1.5 or 2.5 helical turns of DNA results in a GcvA-mediated super-repression of the operon. This repression is dependent on Lrp and is partially dependent on GcvR. Lrp bound to the gcv control region induces a bend in the DNA. Based on these results, a model for gcv regulation is presented in which Lrp plays a primarily structural role, by bending the DNA and GcvA functions as the activator protein.
Stauffer
Lorraine T
LT
Stauffer
George V
GV
D050960:Aminomethyltransferase; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D004269:DNA, Bacterial / Q000737:chemistry* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D019877:Hydroxymethyl and Formyl Transferases / Q000096:biosynthesis / Q000235:genetics*; D007763:Lac Operon; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D008242:Lysogeny; D008957:Models, Genetic; D009690:Nucleic Acid Conformation; D009876:Operon / Q000235:genetics; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics*; D017384:Sequence Deletion; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C095454:GcvA protein, E coli; C095455:GcvR protein, E coli; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D011971:Receptors, Immunologic; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D019877:Hydroxymethyl and Formyl Transferases; D050960:Aminomethyltransferase