Poster: Photosynthesis

Abs # 342: The low carbon dioxide inducible genes Ccp1 and Ccp2 are required for normal growth in a low CO₂ environment in the green alga Chlamydomonas reinhardtii

Presenter:	Pollock, Steve V., pollock@lsu.edu
Authors	Pollock, Steve V. (A)   Prout Jr., Davey L. (A)   Lemaire, Stéphane D. (B)   Moroney, James V. (A)
Affiliations:	(A): Department of Biological Sciences, Louisiana State University (B): Institut de Biotechnologie des Plantes, CNRS, Université Paris-Sud

The unicellular green alga Chlamydomonas reinhardtii acclimates to a low CO₂ environment by modifying the expression of a number of genes. Many of the genes that increase in abundance during acclimation to a low CO₂ environment are under the control of the putative transcription factor Cia5. Two distinct cia5 mutants of Chlamydomonas do not express several of the known low CO₂ inducible genes and do not grow in a low CO₂ environment. Two of the genes under the control of Cia5, Ccp1 and Ccp2, encode polypeptides that have a high degree of similarity to the mitochondrial carrier family of proteins and are localized to the inner chloroplast envelope. RNA interference was successful in dramatically decreasing the abundance of the mRNAs for Ccp1 and Ccp2. The abundance of the Ccp1 and Ccp2 polypeptides were also reduced in the RNAi strains as determined by immunoblot analysis using the ECL detection method. The RNAi strains also grew slower than WT in a low CO₂ environment. (Supported by NSF grant IBN-0212093 and HHMI)