Structures of Selenomonas ruminantium phytase in complex with persulfated phytate: DSP phytase fold and mechanism for sequential substrate hydrolysis.
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.
Chu
Hsing-Mao
HM
Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan.
Guo
Rey-Ting
RT
Lin
Ting-Wan
TW
Chou
Chia-Cheng
CC
Shr
Hui-Lin
HL
Lai
Hui-Lin
HL
Tang
Tsung-Yin
TY
Cheng
Kuo-Joan
KJ
Selinger
Brent L
BL
Wang
Andrew H-J
AH
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
D010833:Phytic Acid; D010832:6-Phytase