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2b4p
From Proteopedia
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Structure of the D223N mutant of Selenomonas ruminantium PTP-like phytase
Overview
PhyA from Selenomonas ruminantium (PhyAsr), is a bacterial protein, tyrosine phosphatase (PTP)-like inositol polyphosphate phosphatase, (IPPase) that is distantly related to known PTPs. PhyAsr has a second, substrate binding site referred to as a standby site and the P-loop, (HCX(5)R) has been observed in both open (inactive) and closed (active), conformations. Site-directed mutagenesis and kinetic and structural, studies indicate PhyAsr follows a classical PTP mechanism of hydrolysis, and has a broad specificity toward polyphosphorylated myo-inositol, substrates, including phosphoinositides. Kinetic and molecular docking, experiments demonstrate PhyAsr preferentially cleaves the 3-phosphate, position of Ins P(6) and will produce Ins(2)P via a highly ordered series, of sequential dephosphorylations: D-Ins(1,2,4,5,6)P(5), Ins(2,4,5,6)P(4), D-Ins(2,4,5)P(3), and D-Ins(2,4)P(2). The data support a distributive, enzyme mechanism and suggest the PhyAsr standby site is involved in the, recruitment of substrate. Structural studies at physiological pH and high, salt concentrations demonstrate the "closed" or active P-loop conformation, can be induced in the absence of substrate. These results suggest PhyAsr, should be reclassified as a D-3 myo-inositol hexakisphosphate, phosphohydrolase and suggest the PhyAsr reaction mechanism is more similar, to that of PTPs than previously suspected.
About this Structure
2B4P is a Single protein structure of sequence from Selenomonas ruminantium with and as ligands. Active as 5-phytase, with EC number 3.1.3.72 Full crystallographic information is available from OCA.
Reference
Kinetic and structural analysis of a bacterial protein tyrosine phosphatase-like myo-inositol polyphosphatase., Puhl AA, Gruninger RJ, Greiner R, Janzen TW, Mosimann SC, Selinger LB, Protein Sci. 2007 Jul;16(7):1368-78. Epub 2007 Jun 13. PMID:17567745
Page seeded by OCA on Wed Jan 23 14:27:59 2008
