title: Phycobilin:cystein-84 biliprotein lyase, a near-universal lyase for cysteine-84-binding sites in cyanobacterial phycobiliproteins.
abstract: Phycobilisomes, the light-harvesting complexes of cyanobacteria and red algae, contain two to four types of chromophores that are attached covalently to seven or more members of a family of homologous proteins, each carrying one to four binding sites. Chromophore binding to apoproteins is catalyzed by lyases, of which only few have been characterized in detail. The situation is complicated by nonenzymatic background binding to some apoproteins. Using a modular multiplasmidic expression-reconstitution assay in Escherichia coli with low background binding, phycobilin:cystein-84 biliprotein lyase (CpeS1) from Anabaena PCC7120, has been characterized as a nearly universal lyase for the cysteine-84-binding site that is conserved in all biliproteins. It catalyzes covalent attachment of phycocyanobilin to all allophycocyanin subunits and to cysteine-84 in the beta-subunits of C-phycocyanin and phycoerythrocyanin. Together with the known lyases, it can thereby account for chromophore binding to all binding sites of the phycobiliproteins of Anabaena PCC7120. Moreover, it catalyzes the attachment of phycoerythrobilin to cysteine-84 of both subunits of C-phycoerythrin. The only exceptions not served by CpeS1 among the cysteine-84 sites are the alpha-subunits from phycocyanin and phycoerythrocyanin, which, by sequence analyses, have been defined as members of a subclass that is served by the more specialized E/F type lyases.
authors.affiliation: College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China. khzhao@163.com
authors.forename: Kai-Hong
authors.initials: KH
authors.lastname: Zhao
authors.forename: Ping
authors.initials: P
authors.lastname: Su
authors.forename: Jun-Ming
authors.initials: JM
authors.lastname: Tu
authors.forename: Xing
authors.initials: X
authors.lastname: Wang
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.forename: Matthias
authors.initials: M
authors.lastname: Plöscher
authors.forename: Lutz
authors.initials: L
authors.lastname: Eichacker
authors.forename: Bei
authors.initials: B
authors.lastname: Yang
authors.forename: Ming
authors.initials: M
authors.lastname: Zhou
authors.forename: Hugo
authors.initials: H
authors.lastname: Scheer
mesh_terms: D001059:Apoproteins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D000458:Cyanobacteria / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003545:Cysteine / Q000235:genetics / Q000378:metabolism*; D008190:Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D015394:Molecular Structure; D008970:Molecular Weight; D052980:Phycobilins / Q000737:chemistry* / Q000494:pharmacology; D052979:Phycobiliproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism
chemical_list: D001059:Apoproteins; D052980:Phycobilins; D052979:Phycobiliproteins; D021122:Protein Subunits; D008190:Lyases; D003545:Cysteine