title: Crystal structure of the stimulatory complex of GTP cyclohydrolase I and its feedback regulatory protein GFRP.
abstract: In the presence of phenylalanine, GTP cyclohydrolase I feedback regulatory protein (GFRP) forms a stimulatory 360-kDa complex with GTP cyclohydrolase I (GTPCHI), which is the rate-limiting enzyme in the biosynthesis of tetrahydrobiopterin. The crystal structure of the stimulatory complex reveals that the GTPCHI decamer is sandwiched by two GFRP homopentamers. Each GFRP pentamer forms a symmetrical five-membered ring similar to beta-propeller. Five phenylalanine molecules are buried inside each interface between GFRP and GTPCHI, thus enhancing the binding of these proteins. The complex structure suggests that phenylalanine-induced GTPCHI x GFRP complex formation enhances GTPCHI activity by locking the enzyme in the active state.
authors.affiliation: Department of Molecular Biology, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Maita
authors.forename: Kengo
authors.initials: K
authors.lastname: Okada
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Hatakeyama
authors.forename: Toshio
authors.initials: T
authors.lastname: Hakoshima
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics; D006136:GTP Cyclohydrolase / Q000037:antagonists & inhibitors / Q000737:chemistry*; D047908:Intracellular Signaling Peptides and Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D004791:Enzyme Inhibitors; C491065:Gchfr protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D011994:Recombinant Proteins; D006136:GTP Cyclohydrolase