title: Intermediate binding of phycocyanobilin to the lyase, CpeS1, and transfer to apoprotein.
abstract: The phycobilin: Cysteine-84-phycobiliprotein lyase, CpeS1, catalyzes phycocyanobilin (PCB) and phycoerythrobilin attachment to nearly all cysteine-84 (consensus sequence) binding sites of phycoerythrin, phycoerythrocyanin, phycocyanin and allophycocyanin (Zhao et al. (2007) Proc Natl Acad Sci 104:14300-14305). We now show that CpeS1 can bind PCB, as assayed by Ni(2+) chelating affinity chromatography. Binding is rapid, and the chromophore is bound in an extended conformation similar to that in phycobiliproteins but only poorly fluorescent. Upon addition of apo-biliproteins, the chromophore is transferred to the latter much slower ( approximately 1 h), indicating that chromophorylated CpeS1 is an intermediate in the enzymatic reaction. In addition, imidazole is bound to PCB, as shown by mass spectroscopy of tryptic digests of the intermediate CpeS1-PCB complex.
authors.affiliation: Department Biologie I-Botanik, Universität München, Menzinger Str. 67, 80638, München, Germany.
authors.forename: Jun-Ming
authors.initials: JM
authors.lastname: Tu
authors.forename: Michaela
authors.initials: M
authors.lastname: Kupka
authors.forename: Stephan
authors.initials: S
authors.lastname: Böhm
authors.forename: Matthias
authors.initials: M
authors.lastname: Plöscher
authors.forename: Lutz
authors.initials: L
authors.lastname: Eichacker
authors.forename: Kai-Hong
authors.initials: KH
authors.lastname: Zhao
authors.forename: Hugo
authors.initials: H
authors.lastname: Scheer
mesh_terms: D001059:Apoproteins / Q000378:metabolism*; D055162:Biocatalysis; D008190:Lyases / Q000378:metabolism*; D052980:Phycobilins / Q000378:metabolism*; D010798:Phycocyanin / Q000378:metabolism*; D011485:Protein Binding; D013056:Spectrophotometry, Ultraviolet
chemical_list: D001059:Apoproteins; D052980:Phycobilins; D010798:Phycocyanin; C011069:phycocyanobilin; D008190:Lyases