title: Activation of transcription initiation from a stable RNA promoter by a Fis protein-mediated DNA structural transmission mechanism.
abstract: The leuV operon of Escherichia coli encodes three of the four genes for the tRNA1Leu isoacceptors. Transcription from this and other stable RNA promoters is known to be affected by a cis-acting UP element and by Fis protein interactions with the carboxyl-terminal domain of the alpha-subunits of RNA polymerase. In this report, we suggest that transcription from the leuV promoter also is activated by a Fis-mediated, DNA supercoiling-dependent mechanism similar to the IHF-mediated mechanism described previously for the ilvP(G) promoter (S. D. Sheridan et al., 1998, J Biol Chem 273: 21298-21308). We present evidence that Fis binding results in the translocation of superhelical energy from the promoter-distal portion of a supercoiling-induced DNA duplex destabilized (SIDD) region to the promoter-proximal portion of the leuV promoter that is unwound within the open complex. A mutant Fis protein, which is defective in contacting the carboxyl-terminal domain of the alpha-subunits of RNA polymerase, remains competent for stimulating open complex formation, suggesting that this DNA supercoiling-dependent component of Fis-mediated activation occurs in the absence of specific protein interactions between Fis and RNA polymerase. Fis-mediated translocation of superhelical energy from upstream binding sites to the promoter region may be a general feature of Fis-mediated activation of transcription at stable RNA promoters, which often contain A+T-rich upstream sequences.
authors.affiliation: Department of Microbiology and Molecular Genetics, College of Medicine, University of California, Irvine, CA 92697, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Opel
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Aeling
authors.forename: Walter M
authors.initials: WM
authors.lastname: Holmes
authors.forename: Reid C
authors.initials: RC
authors.lastname: Johnson
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Benham
authors.forename: G Wesley
authors.initials: GW
authors.lastname: Hatfield
mesh_terms: D001483:Base Sequence; D004269:DNA, Bacterial / Q000378:metabolism; D004278:DNA, Superhelical / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism; D035021:Factor For Inversion Stimulation Protein / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012329:RNA, Bacterial / Q000235:genetics; D012356:RNA, Transfer, Leu / Q000235:genetics*; D015533:Transcriptional Activation
chemical_list: D004269:DNA, Bacterial; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D012329:RNA, Bacterial; D012356:RNA, Transfer, Leu; D012321:DNA-Directed RNA Polymerases; C113275:RNA polymerase alpha subunit