title: Different Modes of Transactivation of Bacteriophage Mu Late Promoters by Transcription Factor C.
abstract: Transactivator protein C is required for the expression of bacteriophage Mu late genes from lys, I, P and mom promoters during lytic life cycle of the phage. The mechanism of transcription activation of mom gene by C protein is well understood. C activates transcription at Pmom by initial unwinding of the promoter DNA, thereby facilitating RNA polymerase (RNAP) recruitment. Subsequently, C interacts with the ß' subunit of RNAP to enhance promoter clearance. The mechanism by which C activates other late genes of the phage is not known. We carried out promoter-polymerase interaction studies with all the late gene promoters to determine the individual step of C mediated activation. Unlike at Pmom, at the other three promoters, RNAP recruitment and closed complex formation are not C dependent. Instead, the action of C at Plys, PI, and PP is during the isomerization from closed complex to open complex with no apparent effect at other steps of initiation pathway. The mechanism of transcription activation of mom and other late promoters by their common activator is different. This distinction in the mode of activation (promoter recruitment and escape versus isomerization) by the same activator at different promoters appears to be important for optimized expression of each of the late genes.
authors.affiliation: Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India.
authors.forename: Ganduri
authors.initials: G
authors.lastname: Swapna
authors.affiliation: Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India.
authors.forename: Vandana
authors.initials: V
authors.lastname: Kumari
authors.affiliation: Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India; Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India.
authors.forename: Valakunja
authors.initials: V
authors.lastname: Nagaraja
mesh_terms: D010583:Bacteriophage mu / Q000235:genetics*; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics*; D001665:Binding Sites / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D015967:Gene Expression Regulation, Viral / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C090591:C protein, Bacteriophage Mu; D004268:DNA-Binding Proteins; D015534:Trans-Activators; D014764:Viral Proteins; D012321:DNA-Directed RNA Polymerases