title: The complete amino-acid sequence and the phylogenetic origin of phycocyanin-645 from the cryptophytan alga Chroomonas sp.
abstract: The first complete amino-acid sequence of the cryptomonad phycobiliprotein phycocyanin-645 from Chroomonas sp. is presented. The alpha 1-subunit contains 70 amino-acid residues and the alpha 2-subunit 80 residues. In each of the alpha-subunits a green, 697-nm absorbing chromophore is covalently bound to Cys18. Both alpha-subunits contain a high number of charged residues. The phycocyanin-645 beta-subunit consists of 177 amino-acid residues. Two phycocyanobilin chromophores are singly bound to Cys beta 82 and Cys beta 158. A purple cryptoviolin-like chromophore is doubly bound to Cys beta 50 and Cys beta 61. Sequence comparisons revealed that the phycocyanin-645 beta-subunit is closely related to red algal phycoerythrin (73% identical amino-acid residues) and not so close to C-phycocyanin (55% identical amino-acid residues). The phycocyanin-645 alpha-subunits represent a special type of phycobiliprotein and a direct relationship to other phycobiliproteins or any light-harvesting polypeptide-pigment complexes could not be derived by sequence comparisons.
authors.affiliation: Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule, Zürich.
authors.forename: W
authors.initials: W
authors.lastname: Sidler
authors.forename: H
authors.initials: H
authors.lastname: Nutt
authors.forename: B
authors.initials: B
authors.lastname: Kumpf
authors.forename: G
authors.initials: G
authors.lastname: Frank
authors.forename: F
authors.initials: F
authors.lastname: Suter
authors.forename: A
authors.initials: A
authors.lastname: Brenzel
authors.forename: W
authors.initials: W
authors.lastname: Wehrmeyer
authors.forename: H
authors.initials: H
authors.lastname: Zuber
mesh_terms: D000595:Amino Acid Sequence; D056890:Eukaryota / Q000235:genetics*; D008969:Molecular Sequence Data; D010798:Phycocyanin / Q000235:genetics*; D010802:Phylogeny; D000461:Rhodophyta / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
chemical_list: C039637:phycocyanin 645; D010798:Phycocyanin