title: SigC, the group 2 sigma factor of RNA polymerase, contributes to the late-stage gene expression and nitrogen promoter recognition in the cyanobacterium Synechocystis sp. strain PCC 6803.
abstract: We examined the role of SigC (Sll0184), a sigma factor of RNA polymerase (RNAP), in a unicellular cyanobacterium, Synechocystis sp. strain PCC 6803. On the inactivation of sigC, which is an Escherichia coli rpoD homolog, cells were viable but had a low survival rate in the stationary phase of growth under normal physiological conditions, indicating that SigC is a group 2 type sigma factor. In analyses of transcript and protein levels using the sigC knockout strain, it was found that expression of glnB, a nitrogen key regulatory gene, is controlled by SigC in the stationary phase. Primer extension revealed that the glnB nitrogen promoter (P2) was specifically recognized by SigC in the stationary phase under conditions of nitrogen starvation. In vitro studies with purified enzymes indicated effective transcription, on supercoiled DNA templates, from P2 by SigC-RNAP with NtcA which is an activator for nitrogen gene transcription. DNase I footprinting also indicated binding and related sites of NtcA and/or RNAP with SigC on the nitrogen promoter. The unique promoter architecture and the mechanism of transcription by RNAP with SigC are also discussed.
authors.affiliation: Laboratory of Molecular Genetics, College of Agriculture, Ibaraki University, Inashiki, Japan. asam@mx.ibaraki.ac.jp
authors.forename: Munehiko
authors.initials: M
authors.lastname: Asayama
authors.forename: Sousuke
authors.initials: S
authors.lastname: Imamura
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yoshihara
authors.forename: Ai
authors.initials: A
authors.lastname: Miyazaki
authors.forename: Naoko
authors.initials: N
authors.lastname: Yoshida
authors.forename: Takashi
authors.initials: T
authors.lastname: Sazuka
authors.forename: Takakazu
authors.initials: T
authors.lastname: Kaneko
authors.forename: Osamu
authors.initials: O
authors.lastname: Ohara
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tabata
authors.forename: Takashi
authors.initials: T
authors.lastname: Osanai
authors.forename: Kan
authors.initials: K
authors.lastname: Tanaka
authors.forename: Hideo
authors.initials: H
authors.lastname: Takahashi
authors.forename: Makoto
authors.initials: M
authors.lastname: Shirai
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000458:Cyanobacteria / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D020868:Gene Silencing; D009584:Nitrogen / Q000378:metabolism*; D051922:PII Nitrogen Regulatory Proteins; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D040901:Proteomics; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D051922:PII Nitrogen Regulatory Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C081467:sigC protein, Bacteria; C404143:PIID regulatory protein, Bacteria; D012321:DNA-Directed RNA Polymerases; D009584:Nitrogen