Abstract
The envelope structure of plastids is often damaged by abiotic stresses, such as low temperature. However, envelope membrane proteins that may protect chloroplasts from abiotic stresses have not been identified yet. We examined the function of a cold inducible gene encoding a putative plastid protein of unknown function by in vitro and in vivo approaches. As a first step of our analysis, we generated Arabidopsis constitutively expressing protein-A fusion construct. Biochemical analyses demonstrated that this protein was an integral membrane protein at the inner envelope of chloroplasts and was processed to a mature form during import into chloroplasts. Gel-filtration and immunoaffinity chromatographies suggested that this protein formed high molecular weight complex but did not stably associate with other inner envelope proteins examined. We will also examine the role of this protein in freezing tolerance of A.thaliana by in vivo approach.
