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| {{STRUCTURE_2b4o| PDB=2b4o | SCENE= }} | | {{STRUCTURE_2b4o| PDB=2b4o | SCENE= }} |
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| '''Structure of the R258K mutant of Selenomonas ruminantium PTP-like phytase'''
| | ===Structure of the R258K mutant of Selenomonas ruminantium PTP-like phytase=== |
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| ==Overview==
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| 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 (HCX5R) 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 P6 and will produce Ins(2)P via a highly ordered series of sequential dephosphorylations: D-Ins(1,2,4,5,6)P5, Ins(2,4,5,6)P4, D-Ins(2,4,5)P3, and D-Ins(2,4)P2. 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17567745}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17567745 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17567745}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Ionic strength]] | | [[Category: Ionic strength]] |
| [[Category: Ptp-like]] | | [[Category: Ptp-like]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 19:51:02 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 17:40:32 2008'' |
