DNA unwinding mechanism for the transcriptional activation of momP1 promoter by the transactivator protein C of bacteriophage Mu.
Transcription factor-induced conformational changes in DNA are one of the mechanisms of transcription activation. C protein of bacteriophage Mu appears to transactivate the mom gene of the phage by this mode. DNA binding by C to its site leads to torsional changes that seem to compensate for a weak momP1 promoter having a suboptimal spacing of 19 bp between the poor -35 and -10 elements. The C-mediated unwinding could realign the promoter elements for RNA polymerase recruitment to the reoriented promoter. In this study, the model has been tested by mutational analysis of the spacer region of momP1 and by assessing the strength of the mutant promoters. The response to C-mediated transactivation was dependent on the spacer length of the promoters. Mutants with 17-bp spacing between the two promoter elements showed reduced activity in the presence of the transactivator as compared with their basal level. A synthetic promoter with near consensus promoter elements and optimal 17-bp spacing was also tested to evaluate the model. The results imply a role for C-mediated unwinding in mom transcription activation.
Basak
S
S
Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India.
Nagaraja
V
V
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D010583:Bacteriophage mu / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D001665:Binding Sites; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011487:Protein Conformation; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism*; D015533:Transcriptional Activation; D014764:Viral Proteins; D001616:beta-Galactosidase / Q000378:metabolism
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C090591:C protein, Bacteriophage Mu; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D015534:Trans-Activators; D014764:Viral Proteins; D004247:DNA; D012321:DNA-Directed RNA Polymerases; D001616:beta-Galactosidase