title: Specific contacts of the -35 region of the galP1 promoter by RNA polymerase inhibit GalR-mediated DNA looping repression.
abstract: The P1 promoter of the galactose operon in Escherichia coli is one of the best studied examples of 'extended -10' promoters. Recognition of the P1 promoter does not require specific contacts between RNA polymerase and its poor -35 element. To investigate whether specific recognition of the -35 element would affect the regulation of P1 by GalR, we mutagenized the -35 element of P1, isolated variants of the -35 element and studied the regulation of the mutant promoters by in vitro transcription assays and by mathematical modeling. The results show that the GalR-mediated DNA loop is less efficient in repressing P1 transcription when RNA polymerase binds to the -10 and -35 elements concomitantly. Our results suggest that promoters that lack specific -35 element recognition allow decoupling of local chromosome structure from transcription initiation.
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD, USA.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Csiszovszki
authors.forename: Dale E A
authors.initials: DE
authors.lastname: Lewis
authors.forename: Phuoc
authors.initials: P
authors.lastname: Le
authors.forename: Kim
authors.initials: K
authors.lastname: Sneppen
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Semsey
mesh_terms: D001483:Base Sequence; D016384:Consensus Sequence; D004269:DNA, Bacterial / Q000737:chemistry*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D009876:Operon; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C050993:Galactose repressor proteins; D012097:Repressor Proteins; D012321:DNA-Directed RNA Polymerases