title: SIG1, a sigma factor for the chloroplast RNA polymerase, differently associates with multiple DNA regions in the chloroplast chromosomes in vivo.
abstract: Chloroplasts have their own DNA and gene expression systems. Transcription in chloroplasts is regulated by two types of RNA polymerase, nuclear-encoded plastid RNA polymerase (NEP) and plastid-encoded plastid RNA polymerase (PEP), and multiple sigma factors for PEP. To study transcriptional regulation in chloroplasts, a molecular genetic approach has extensively been used. However, this method may include indirect effects, and it cannot be applied to the analysis of factors essential to survival. These limitations make understanding specific regulation by transcription factors difficult. Chromatin immunoprecipitation (ChIP) is a powerful and useful tool for obtaining information on transcription-factor binding sites; it can directly detect dynamic changes in their interaction patterns in vivo. To further understand transcriptional regulation in chloroplasts, we here established a ChIP-based method in Arabidopsis thaliana and analyzed the binding pattern of a chloroplast sigma factor, SIG1. We found that SIG1 specifically binds to newly identified target promoters as well as to a set of promoters of genes whose mRNA expression is dependent on OsSIG1 in rice and that this binding changed in response to high-light stress. These results suggested that the ChIP-based approach is very useful in understanding transcriptional regulation of chloroplast genes and can overcome several problems posed by conventional methods.
authors.affiliation: Division of Applied Biological Chemistry, Graduate School of Horticulture, Chiba University, Matsudo 648, Matsudo, Chiba 271-8510, Japan. mhanaoka@faculty.chiba-u.jp.
authors.forename: Mitsumasa
authors.initials: M
authors.lastname: Hanaoka
authors.forename: Maiko
authors.initials: M
authors.lastname: Kato
authors.forename: Misato
authors.initials: M
authors.lastname: Anma
authors.forename: Kan
authors.initials: K
authors.lastname: Tanaka
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000201:enzymology / Q000235:genetics*; D047369:Chromatin Immunoprecipitation; D032461:Chromosomes, Plant / Q000235:genetics*; D018744:DNA, Plant / Q000737:chemistry / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008027:Light; D012275:Oryza / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D036226:Seedlings / Q000378:metabolism; D012808:Sigma Factor / Q000235:genetics* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D018744:DNA, Plant; D012333:RNA, Messenger; D011994:Recombinant Proteins; D012808:Sigma Factor; D012321:DNA-Directed RNA Polymerases