title: HO1 and PcyA proteins involved in phycobilin biosynthesis form a 1:2 complex with ferredoxin-1 required for photosynthesis.
abstract: The HO1 and PcyA genes, encoding heme oxygenase-1 (HO1) and phycocyanobilin (PCB):ferredoxin (Fd) oxidoreductase (PcyA), respectively, are required for chromophore synthesis in photosynthetic light-harvesting complexes, photoreceptors, and circadian clocks. In the PCB biosynthetic pathway, heme first undergoes cleavage to form biliverdin. I confirmed that Fd1 induced the formation of a stable and functional HO1 complex by the gel mobility shift assay. Furthermore, analysis by a chemical cross-linking technique designed to detect protein-protein interactions revealed that HO1 and PcyA directly interact with Fd in a 1:2 ratio. Thus, Fd1, a one-electron carrier protein in photosynthesis, drives the phycobilin biosynthetic pathway.
authors.affiliation: Research Center for Advanced Agrotechnology and Biotechnology, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan. okadak@recab.tut.ac.jp
authors.forename: Ken
authors.initials: K
authors.lastname: Okada