Abstract
Land plants posses chlorophyll a and chlorophyll b in their light harvesting systems. The composition of these pigments varies in response to their light environments. Biosynthesis of chlorophyll b is involved in control of LHC accumulation and antenna size. In order to elucidate the mechanism regulating the biosynthesis of chlorophyll b, we analyzed an Arabidopsis chlorina5 (ch5) mutant deficient in chlorophyll b accumulation.
We identified the ch5 gene by positional cloning. It encodes a putative protease. Similar sequences were found in a wide rage of organisms, the most similar ones being found among the photosynthetic organisms.
Interestingly, accumulation of mRNA for chlorophyllide a oxygenase, the chlorophyll b synthesizing enzyme, was increased in ch5. We will discuss the possible regulatory mechanism of chlorophyll b biosynthesis involving a protease.
