Immunological Identification of Polypeptides in Photosystem II Complexes from the Cyanobacterium Anacystis nidulans

Abstract

Abstract Photosystem II complexes from the cyanobacterium Anacystis nidulans have been investigated by Western blots with antisera raised against four photosystem II peptides from plants and with an antiserum raised against the soluble L-amino acid oxidase protein from/1. nidulans to achieve an iden­tification of the polypeptides - especially of the L-amino acid oxidase related protein - in isolated photosystem II complexes. Anacystis photosystem II complexes which were solubilized with lauryldimethylamine N-oxide and purified by sucrose cushion and sucrose gradient centrifugation, contained as major Coomassie brilliant blue stained polypeptides a 71 kDa band of unknown identity, a 62 kDa band, which partly contained D-l, a 55 and 49 kDa band which were immuno-reactive with an antiserum to the 47 kDa peptide of tobacco PS II complexes, and three distinct bands in the 30 kDa region. These latter bands could be identified as the extrinsic Mn stabilizing peptide (27-30 kDa), D-l (30-33 kDa) and a 36 kDa peptide (35 - 38 kDa) which crossreacted with the antiserum raised against the soluble L-amino acid oxidase protein of 50 kDa. These results suggest that the 36 kDa peptide present in purified photosystem II complexes from A. nidulans might be a processed form of the soluble 50 kDa L-amino acid oxidase protein.