New linker proteins in phycobilisomes isolated from the cyanobacterium Gloeobacter violaceus PCC 7421

Two new linker proteins were identified by peptide mass fingerprinting in phycobilisomes isolated from the cyanobacterium Gloeobacter violaceus PCC 7421. The proteins were products of glr1262 and glr2806. Three tandem phycocyanin linker motifs similar to CpcC were present in each. The glr1262 product most probably functions as a rod linker connecting phycoerythrin and phycocyanin, while the glr2806 product may function as a rod-core linker. We have designated these two proteins CpeG and CpcJ, respectively. The morphology of phycobilisomes in G. violaceus has been reported to be a bundle-like shape with six rods, consistent with the proposed functions of these linkers.