Significant energy transfer from CpcG2-phycobilisomes to photosystem I in the cyanobacterium Synechococcus sp PCC 7002 in the absence of ApcD-dependent state transitions

Hemidiscoidal phycobilisomes (PBS), the major light harvesting complexes of photosynthesis in most cyanobacteria, are composed of rods and cores, which are linked by the linker CpcG1 (L-RC). Another type of PBS, CpcG2-PBS exits and their function in energy transfer has not been fully under-stood. We measured growth rates, absorption cross-sections and quantum efficiency of photosystem I in mutant strains of Synechococcus PCC sp. 7002 lacking the linker CpcG2. Our results showed that energy transfer from CpcG2-PBS to PSI in the absence of state transitions could be significant under PBS-absorbing light and energy transfer from two types of PBS is independent to each other. Evidence also suggested that CpcG2 anchors the CpcG2-PBS to thylakoid membranes. (C) 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.Biochemistry & Molecular BiologyBiophysicsCell BiologySCI(E)PubMed3ARTICLE162342-234558