title: Tools for regulated gene expression in the chloroplast of Chlamydomonas.
abstract: The green unicellular alga Chlamydomonas reinhardtii has emerged as a very attractive model system for chloroplast genetic engineering. Algae can be transformed readily at the chloroplast level through bombardment of cells with a gene gun, and transformants can be selected using antibiotic resistance or phototrophic growth. An inducible chloroplast gene expression system could be very useful for several reasons. First, it could be used to elucidate the function of essential chloroplast genes required for cell growth and survival. Second, it could be very helpful for expressing proteins which are toxic to the algal cells. Third, it would allow for the reversible depletion of photosynthetic complexes thus making it possible to study their biogenesis in a controlled fashion. Fourth, it opens promising possibilities for hydrogen production in Chlamydomonas. Here we describe an inducible/repressible chloroplast gene expression system in Chlamydomonas in which the copper-regulated Cyc6 promoter drives the expression of the nuclear Nac2 gene encoding a protein which is targeted to the chloroplast where it acts specifically on the chloroplast psbD 5'-untranslated region and is required for the stable accumulation of the psbD mRNA and photosystem II. The system can be used for any chloroplast gene or transgene by placing it under the control of the psbD 5'-untranslated region.
authors.affiliation: Department of Molecular Biology, University of Geneva, Geneva, Switzerland.
authors.forename: Jean-David
authors.initials: JD
authors.lastname: Rochaix
authors.forename: Raymond
authors.initials: R
authors.lastname: Surzycki
authors.forename: Silvia
authors.initials: S
authors.lastname: Ramundo
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D019470:Biolistics / Q000379:methods; D016825:Chlamydomonas reinhardtii / Q000235:genetics*; D002736:Chloroplasts / Q000235:genetics* / Q000378:metabolism; D003300:Copper / Q000494:pharmacology; D045365:Cytochromes c6 / Q000235:genetics; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D009713:Nucleotidyltransferases / Q000235:genetics; D045332:Photosystem II Protein Complex / Q000235:genetics; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D012097:Repressor Proteins / Q000235:genetics; D014170:Transformation, Genetic; D019076:Transgenes / Q000235:genetics*
chemical_list: D020121:5' Untranslated Regions; D045365:Cytochromes c6; D045332:Photosystem II Protein Complex; D012333:RNA, Messenger; D012097:Repressor Proteins; D003300:Copper; D009713:Nucleotidyltransferases; C020565:gentamicin 2''-nucleotidyltransferase