Strong interaction of CpcL with photosystem I cores induced in heterocysts of Anabaena sp. PCC 7120.

ABSTRACT

Phycobilisomes (PBSs) are photosynthetic light-harvesting antennae and appear to be loosely bound to photosystem I (PSI). We previously found unique protein bands in each PSI fraction in heterocysts of Anabaena sp. PCC 7120 by two-dimensional blue native/SDS-PAGE; however, the protein bands have not been identified. Here we analyzed the protein bands by mass spectrometry, which were identified as CpcL, one of the components in PBSs. As different composition and organization of Anabaena PSI-PBS supercomplexes were observed, the expression and binding properties of PBSs including CpcL to PSIs in this cyanobacterium may be diversified in response to its living environments.