CRYPTOMONAD BILIPROTEINS - BILIN TYPES AND LOCATIONS

Two cryptophycean phycocyanins (Cr-PCs), Hemiselmis strain HP9001 Cr-P C 612 and Falcomonas daucoides Cr-PC 569 were purified and characteriz ed with respect to bilin numbers, types and locations. Each biliprotei n carried one bilin on the ct subunit and three on the beta subunit. C r-PC 612 carried phycocyanobilin at alpha-Cys-18, beta-Cys-82, and bet a-Cys-158, and a doubly-linked 15,16-dihydrobiliverdin at beta-DiCys-5 0,61. Cr-PC 569 carried phycocyanobilin at alpha-Cys-18 and beta-Cys-8 2, a singly-linked Bilin 584 at beta-Cys-158, and a doubly-linked Bili n 584 at beta-DiCys-50,61. This work, in conjunction with earlier stud ies on Cr-PE 545, Cr-PE 555, Cr-PE 566, and Cr-PC 645, shows that ther e is no conserved location for the bilin with longest wavelength visib le absorption band among these proteins, and, consequently, that there is no conserved energy transfer pathway common to all native cryptoph ycean biliproteins. Only phycocyanobilin or phycoerythrobilin is found at beta-Cys-82; there is greater bilin variability at the other three attachment sites.