Characterization of a cDNA encoding a PSII-associated chlorophyll a/b-binding protein (CAB) from Chlamydomonas moewusii fitting into neither type I nor type II.

A full-length 1010-bp cDNA clone from Chlamydomonas moewusii coding for the precursor of a chlorophyll a/b-binding protein (CAB) was characterized. Northern analysis shows hybridization to a single 1150-base light-stimulated mRNA. Complementary hybrid-selected mRNAs were translated in vitro; SDS-PAGE indicates the synthesis of three polypeptides of 25, 27 and 28 kDa. Comparison of the deduced polypeptide sequence with other published CABs reveals greater similarity with PSII-associated proteins but, as with other algal CABs, our sequence does not meet established criteria for inclusion into either type I or type II, so branching of CABs into two types seems to have occurred after the divergence between algae and land plants.