Activation of transcription initiation from a stable RNA promoter by a Fis protein-mediated DNA structural transmission mechanism.
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.
Opel
Michael L
ML
Department of Microbiology and Molecular Genetics, College of Medicine, University of California, Irvine, CA 92697, USA.
Aeling
Kimberly A
KA
Holmes
Walter M
WM
Johnson
Reid C
RC
Benham
Craig J
CJ
Hatfield
G Wesley
GW
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
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