The role of a LCIB/LCIC complex during acclimation to CO₂-limiting stress in a green alga, Chlamydomonas reinhardtii

Abstract

Acclimation to CO₂-limiting stress conditions needs the monitoring of the environmental CO₂ levels and the following induction of low-CO₂ responsive genes for the carbon-concentrating mechanism (CCM). We focus on understanding roles of the low-CO₂ responsive gene products in CCM. Using cDNA array, we previously identified two genes, LciB and LciC, encoding approximately 50 kDa soluble proteins, showing rapid induction under CO₂-limiting stress conditions in light. LciB complemented the Chlamydomonas mutant, pmp1, which shows reduced CO₂-transport activity and high-CO₂ requiring phenotype under low-CO₂ condition. We examined the subcellular localization of LCIB and LCIC protein by immuno-histochemistry and also found that LCIB and LCIC form a complex in vivo. Based on the above observations, function of the LCIB/LCIC complex will be discussed.