title: CO(2)-responsive transcriptional regulation of CAH1 encoding carbonic anhydrase is mediated by enhancer and silencer regions in Chlamydomonas reinhardtii.
abstract: Chlamydomonas reinhardtii adapts to the stress of CO(2)-limiting conditions through the induction of a set of genes including CAH1, which encodes a periplasmic carbonic anhydrase. CAH1 is up-regulated under low-CO(2) conditions (air containing 0.04% [v/v] CO(2)) in the presence of light, whereas it is down-regulated under high-CO(2) conditions (5% [v/v] CO(2)) or in the dark. In an effort to identify cis-elements involved in the transcriptional regulation of CAH1, a series of 5'-nested deletions of the region upstream of CAH1 were fused to a promoterless arylsulfatase reporter gene (ARS). The upstream region from -651 to +41 relative to the transcription start site was sufficient to regulate the expression of ARS with kinetics similar to those of endogenous CAH1. Deletion of the region between -651 and -294 resulted in a significant decrease in the level of arylsulfatase activity expressed under low-CO(2) conditions. The 543-bp upstream region from -651 to -109, without any promoter elements, CAAT-box, or TATA-box, could confer CO(2) and light responsiveness on the beta(2)-tubulin minimal promoter. This 543-bp region was divided into two parts: a 358-bp silencer region from -651 to -294, which represses the minimal promoter activity under high-CO(2) conditions, and a 185-bp enhancer region from -293 to -109, which activates the promoter under low-CO(2) conditions in the presence of light.
authors.affiliation: Laboratory of Plant Molecular Biology, Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: K i
authors.initials: Ki
authors.lastname: Kucho
authors.forename: K
authors.initials: K
authors.lastname: Ohyama
authors.forename: H
authors.initials: H
authors.lastname: Fukuzawa
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D002245:Carbon Dioxide / Q000494:pharmacology / Q000502:physiology*; D002256:Carbonic Anhydrases / Q000096:biosynthesis / Q000235:genetics*; D016825:Chlamydomonas reinhardtii / Q000201:enzymology* / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D020868:Gene Silencing; D017930:Genes, Reporter; D008027:Light; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D014158:Transcription, Genetic
chemical_list: D020121:5' Untranslated Regions; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D002245:Carbon Dioxide; D002256:Carbonic Anhydrases