Maita N, Okada K, Hirotsu S, Hatakeyama K, Hakoshima T
Department of Molecular Biology, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan.
Acta Crystallogr D Biol Crystallogr. 2001 Aug;57(Pt 8):1153-6. doi: 10.1107/s0907444901005558. Epub 2001 Jul 23.
Mammalian GTP cyclohydrolase I is a decameric enzyme in the first and rate-limiting step in the biosynthesis of tetrahydrobiopterin, which is an essential cofactor for enzymes producing neurotransmitters such as catecholamines and for nitric oxide synthases. The enzyme is dually regulated by its feedback regulatory protein GFRP in the presence of its stimulatory effector phenylalanine and its inhibitory effector biopterin. Here, both the stimulatory and inhibitory complexes of rat GTP cyclohydrolase I bound to GFRP were crystallized by vapour diffusion. Diffraction data sets at resolutions of 3.0 and 2.64 A were collected for the stimulatory and inhibitory complexes, respectively. Each complex consists of two GTPCHI pentamer rings and two GFRP pentamer rings, with pseudo-52 point-group symmetry.
哺乳动物鸟苷三磷酸环化水解酶I是四氢生物蝶呤生物合成第一步也是限速步骤中的一种十聚体酶，四氢生物蝶呤是诸如儿茶酚胺等神经递质生成酶以及一氧化氮合酶的必需辅助因子。在其刺激效应物苯丙氨酸和抑制效应物生物蝶呤存在的情况下，该酶受到其反馈调节蛋白GFRP的双重调节。在此，通过气相扩散法使与GFRP结合的大鼠鸟苷三磷酸环化水解酶I的刺激复合物和抑制复合物都结晶。分别为刺激复合物和抑制复合物收集了分辨率为3.0 Å和2.64 Å的衍射数据集。每个复合物由两个鸟苷三磷酸环化水解酶I五聚体环和两个GFRP五聚体环组成，具有伪52点群对称性。
