title: Structures of Selenomonas ruminantium phytase in complex with persulfated phytate: DSP phytase fold and mechanism for sequential substrate hydrolysis.
abstract: Various inositide phosphatases participate in the regulation of inositol polyphosphate signaling molecules. Plant phytases are phosphatases that hydrolyze phytate to less-phosphorylated myo-inositol derivatives and phosphate. The phytase from Selenomonas ruminantium shares no sequence homology with other microbial phytases. Its crystal structure revealed a phytase fold of the dual-specificity phosphatase type. The active site is located near a conserved cysteine-containing (Cys241) P loop. We also solved two other crystal forms in which an inhibitor, myo-inositol hexasulfate, is cocrystallized with the enzyme. In the "standby" and the "inhibited" crystal forms, the inhibitor is bound, respectively, in a pocket slightly away from Cys241 and at the substrate binding site where the phosphate group to be hydrolyzed is held close to the -SH group of Cys241. Our structural and mutagenesis studies allow us to visualize the way in which the P loop-containing phytase attracts and hydrolyzes the substrate (phytate) sequentially.
authors.affiliation: Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Hsing-Mao
authors.initials: HM
authors.lastname: Chu
authors.forename: Rey-Ting
authors.initials: RT
authors.lastname: Guo
authors.forename: Ting-Wan
authors.initials: TW
authors.lastname: Lin
authors.forename: Chia-Cheng
authors.initials: CC
authors.lastname: Chou
authors.forename: Hui-Lin
authors.initials: HL
authors.lastname: Shr
authors.forename: Hui-Lin
authors.initials: HL
authors.lastname: Lai
authors.forename: Tsung-Yin
authors.initials: TY
authors.lastname: Tang
authors.forename: Kuo-Joan
authors.initials: KJ
authors.lastname: Cheng
authors.forename: Brent L
authors.initials: BL
authors.lastname: Selinger
authors.forename: Andrew H-J
authors.initials: AH
authors.lastname: Wang
mesh_terms: D010832:6-Phytase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D006868:Hydrolysis; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010833:Phytic Acid / Q000378:metabolism*; D011487:Protein Conformation; D017510:Protein Folding; D020357:Selenomonas / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D010833:Phytic Acid; D010832:6-Phytase