Different roles for ApcD and ApcF in Synechococcus elongatus and Synechocystis sp. PCC 6803 phycobilisomes

CALZADILLA P.I.; MUZZOPAPPA, FERNANDO; SÉTIF, PIERRE; KIRILOVSKY, DIANA

Barcelona

Congreso; 2019 ESP-IUPB World Congress; 2019

The phycobilisome, the cyanobacterial light harvesting complex, is a huge phycobiliprotein containing extramembranecomplex, formed by a core from which rods radiate. The phycobilisome has evolved to efficiently absorb sun energyand transfer it to the photosystems via the last energy acceptors of the phycobilisome, ApcD and ApcE. ApcF alsoaffects energy transfer by interacting with ApcE. In this work we studied the role of ApcD and ApcF in energy transferand state transitions in Synechococcus elongatus and Synechocystis PCC6803. Our results demonstrate that theseproteins have different roles in both processes in the two strains. The lack of ApcD and ApcF inhibits state transitionsin Synechocystis but not in S. elongatus. In addition, lack of ApcF decreases energy transfer to both photosystemsonly in Synechocystis, while the lack of ApcD alters energy transfer to photosystem I only in S. elongatus. Thus,conclusions based on results obtained in one cyanobacterial strain cannot be systematically transferred to otherstrains and the putative role(s) of phycobilisomes in state transitions need to be reconsidered.