title: Promoter activation by CII, a potent transcriptional activator from bacteriophage 186.
abstract: The lysogeny promoting protein CII from bacteriophage 186 is a potent transcriptional activator, capable of mediating at least a 400-fold increase in transcription over basal activity. Despite being functionally similar to its counterpart in phage λ, it shows no homology at the level of protein sequence and does not belong to any known family of transcriptional activators. It also has the unusual property of binding DNA half-sites that are separated by 20 base pairs, center to center. Here we investigate the structural and functional properties of CII using a combination of genetics, in vitro assays, and mutational analysis. We find that 186 CII possesses two functional domains, with an independent activation epitope in each. 186 CII owes its potent activity to activation mechanisms that are dependent on both the σ(70) and α C-terminal domain (αCTD) components of RNA polymerase, contacting different functional domains. We also present evidence that like λ CII, 186 CII is proteolytically degraded in vivo, but unlike λ CII, 186 CII proteolysis results in a specific, transcriptionally inactive, degradation product with altered self-association properties.
authors.affiliation: Department of Biochemistry, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Iain
authors.initials: I
authors.lastname: Murchland
authors.affiliation: Department of Biochemistry, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Ahlgren-Berg
authors.affiliation: Department of Biochemistry, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: David G
authors.initials: DG
authors.lastname: Priest
authors.affiliation: Department of Biochemistry, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Ian B
authors.initials: IB
authors.lastname: Dodd
authors.affiliation: Department of Biochemistry, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia. Electronic address: keith.shearwin@adelaide.edu.au.
authors.forename: Keith E
authors.initials: KE
authors.lastname: Shearwin
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004252:DNA Mutational Analysis; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry; D000939:Epitopes / Q000737:chemistry; D013058:Mass Spectrometry; D008957:Models, Genetic; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009841:Oligonucleotides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012808:Sigma Factor / Q000737:chemistry; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D000939:Epitopes; D009841:Oligonucleotides; D012808:Sigma Factor; D014157:Transcription Factors; D014764:Viral Proteins; C039000:cII protein, bacteriophage lambda; C081775:RNA polymerase sigma 70; D012321:DNA-Directed RNA Polymerases
keywords: Bacterial Transcription; Bacteriophage; Gene Transcription; Mutational Screen; Promoter; Protein Structure-Function; Proteolysis; RNA Polymerase