Abstract
The core of the phycobilisomes of Synechococcus 6301 (Anacystis nidulans) strain AN112 consists of two cylindrical elements each made up of the same four distinct subcomplexes: A (alpha AP beta AP)3; B (alpha AP beta AP)2 . 18.3K . 75K; C (alpha 1APB alpha 2AP beta 3AP) . 10.5K; and D (alpha AP beta AP)3 . 10.5K, where alpha AP and beta AP are the subunits of allophycocyanin, alpha APB is the subunit of allophycocyanin B, and 18.3K, 75K, and 10.5K are polypeptides of 18,300, 75,000, and 10,500 Da, respectively. An 18 S subassembly containing subcomplexes A and B has previously been characterized (Yamanaka, G., Lundell, D. J., and Glazer, A. N. (1982) J. Biol. Chem. 257, 4077-4086; Lundell, D. J., and Glazer, A. N. (1983) J. Biol. Chem. 258, 894-901, 902-908). A ternary core subassembly, containing complexes A, B, and C, was isolated from a limited tryptic digest of AN112 phycobilisomes and characterized with respect to composition and spectroscopic properties. Isolation of this ternary subassembly also establishes that subcomplex D must occupy a terminal position in each of the two core cylinders. Spectroscopic studies of the individual complexes, A-D, of the subassemblies AB and ABC, and of intact AN112 phycobilisomes showed c...Continue Reading