PDBsum entry 2pt0

Hydrolase

PDB id

2pt0

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Contents

			Protein chains

					313 a.a. *

			Ligands

					GOL ×3

			Waters ×686

* Residue conservation analysis

PDB id:

2pt0

Links

Name:

Hydrolase

Title:

Structure of selenomonas ruminantium ptp-like phytase with the active site cysteine oxidized to cysteine-sulfonic acid

Structure:

Myo-inositol hexaphosphate phosphohydrolase. Chain: a, b. Engineered: yes

Source:

Selenomonas ruminantium. Organism_taxid: 971. Gene: phya. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.70Å

R-factor:

0.177

R-free:

0.190

Authors:

R.J.Gruninger,L.B.Selinger,S.C.Mosimann

Key ref:

R.J.Gruninger et al. (2008). Effect of ionic strength and oxidation on the P-loop conformation of the protein tyrosine phosphatase-like phytase, PhyAsr. Febs J, 275, 3783-3792. PubMed id: 18573100

Date:

07-May-07

Release date:

13-May-08

PROCHECK

	Headers

	References

Protein chains

Q7WUJ1 (Q7WUJ1_SELRU) - Myo-inositol hexaphosphate phosphohydrolase from Selenomonas ruminantium

Seq: Struc:					346 a.a. 313 a.a.*

Key:

PfamA domain

Secondary structure

CATH domain

* PDB and UniProt seqs differ at 1 residue position (black cross)



		Enzyme reactions

Enzyme class:

E.C.?

[IntEnz] [ExPASy] [KEGG] [BRENDA]

	Febs J 275:3783-3792 (2008)
PubMed id: 18573100

Effect of ionic strength and oxidation on the P-loop conformation of the protein tyrosine phosphatase-like phytase, PhyAsr.
R.J.Gruninger, L.B.Selinger, S.C.Mosimann.

ABSTRACT

The protein tyrosine phosphatase (PTP)-like phytase, PhyAsr, from Selenomonas ruminantium is a novel member of the PTP superfamily, and the only described member that hydrolyzes myo-inositol-1,2,3,4,5,6-hexakisphosphate. In addition to the unique substrate specificity of PhyAsr, the phosphate-binding loop (P-loop) has been reported to undergo a conformational change from an open (inactive) to a closed (active) conformation upon ligand binding at low ionic strength. At high ionic strengths, the P-loop was observed in the closed, active conformation in both the presence and absence of ligand. To test whether the P-loop movement can be induced by changes in ionic strength, we examined the effect that ionic strength has on the catalytic efficiency of PhyAsr, and determined the structure of the enzyme at several ionic strengths. The catalytic efficiency of PhyAsr is highly sensitive to ionic strength, with a seven-fold increase in k(cat)/K(m) and a ninefold decrease in K(m) when the ionic strength is increased from 100 to 500 mm. Surprisingly, the P-loop is observed in the catalytically competent conformation at all ionic strengths, despite the absence of a ligand. Here we provide structural evidence that the ionic strength dependence of PhyAsr and the conformational change in the P-loop are not linked. Furthermore, we demonstrate that the previously reported P-loop conformational change is a result of irreversible oxidation of the active site thiolate. Finally, we rationalize the observed P-loop conformational changes observed in all oxidized PTP structures.

Literature references that cite this PDB file's key reference

PubMed id

Reference

19371084

S.J.Tsai, U.Sen, L.Zhao, W.B.Greenleaf, J.Dasgupta, E.Fiorillo, V.Orrú, N.Bottini, and X.S.Chen (2009).
Crystal structure of the human lymphoid tyrosine phosphatase catalytic domain: insights into redox regulation .

Biochemistry, 48, 4838-4845.

PDB code:

3h2x

The most recent references are shown first. Citation data come partly from CiteXplore and partly from an automated harvesting procedure. Note that this is likely to be only a partial list as not all journals are covered by either method. However, we are continually building up the citation data so more and more references will be included with time. Where a reference describes a PDB structure, the PDB code is shown on the right.