Role of the Longest Arm of Phycobilisome Core-Membrane Linker in Assembling the Phycobilisomes From Synechocystis sp. PCC 6803

The helix-loop-helix element of Arm2 is essential for the longitudinal integrity of the PBS core and is a prerequisite for state transitions. These results suggest that state transitions may involve longitudinal rearrangements within the PBS structure, rather than lateral movements of the two halves, implicating that state transitions result from the longitudinal instead of the lateral moves of the two halves of the PBSs.