1i7y
From Proteopedia
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CRYSTAL STRUCTURE OF C-PHYCOCYANIN OF SYNECHOCOCCUS VULCANUS AT 2.5 ANGSTROMS.
Overview
The crystal structure of the light-harvesting phycobiliprotein, c-phycocyanin from the thermophilic cyanobacterium Synechochoccus vulcanus, has been determined by molecular replacement to 2.5 A resolution. The, crystal belongs to space group R32 with cell parameters a=b=188.43 A, c=61.28 A, alpha=beta=90 degrees, gamma=120 degrees, with one (alphabeta), monomer in the asymmetric unit. The structure has been refined to a, crystallographic R factor of 20.2 % (R-free factor is 24.4 %), for all, data to 2.5 A. The crystals were grown from phycocyanin (alphabeta)(3), trimers that form (alphabeta)(6) hexamers in the crystals, in a fashion, similar to other phycocyanins. Comparison of the primary, tertiary and, quaternary structures of the S. vulcanus phycocyanin structure with, phycocyanins from both the mesophilic Fremyella diplsiphon and the, thermophilic Mastigocladus laminosus were performed. We show that each, level of assembly of oligomeric phycocyanin, which leads to the formation, of the phycobilisome structure, can be stabilized in thermophilic, organisms by amino acid residue substitutions. Each substitution can form, additional ionic interactions at critical positions of each association, interface. In addition, a significant shift in the position of ring D of, the B155 phycocyanobilin cofactor in the S. vulcanus phycocyanin, enables, the formation of important polar interactions at both the (alphabeta), monomer and (alphabeta)(6) hexamer association interfaces.
About this Structure
1I7Y is a Protein complex structure of sequences from Thermosynechococcus vulcanus with CYC and MEN as ligands. Full crystallographic information is available from OCA.
Reference
Structure of c-phycocyanin from the thermophilic cyanobacterium Synechococcus vulcanus at 2.5 A: structural implications for thermal stability in phycobilisome assembly., Adir N, Dobrovetsky Y, Lerner N, J Mol Biol. 2001 Oct 12;313(1):71-81. PMID:11601847
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