PDBsum entry 1a5y

Hydrolase

PDB id: 1a5y

Contents

Protein chain

284 a.a. *

Waters ×222

* Residue conservation analysis

PDB id:

1a5y

Name:

Hydrolase

Title:

Protein tyrosine phosphatase 1b cysteinyl-phosphate intermediate

Structure:

Protein tyrosine phosphatase 1b. Chain: a. Fragment: catalytic domain, residues 1 - 321. Engineered: yes. Other_details: phosphate link to cys 215

Source:

Homo sapiens. Human. Organism_taxid: 9606. Cell_line: ba834. Cellular_location: er membrane. Expressed in: escherichia coli. Expression_system_taxid: 562. Expression_system_cell_line: ba834.

Resolution:

2.50Å R-factor: 0.205 R-free: 0.281

Authors:

A.D.P.Pannifer,A.J.Flint,N.K.Tonks,D.Barford

Key ref:

A.D.Pannifer et al. (1998). Visualization of the cysteinyl-phosphate intermediate of a protein-tyrosine phosphatase by x-ray crystallography. J Biol Chem, 273, 10454-10462. PubMed id: 9553104 DOI: 10.1074/jbc.273.17.10454

Date:

19-Feb-98 Release date: 17-Jun-98

Protein chain

P18031  (PTN1_HUMAN) -  Tyrosine-protein phosphatase non-receptor type 1 from Homo sapiens

Seq: 435 a.a.

Struc: 284 a.a.*

* PDB and UniProt seqs differ at 4 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.3.1.3.48 - protein-tyrosine-phosphatase.
• Reaction: O-phospho-L-tyrosyl-[protein] + H2O = L-tyrosyl-[protein] + phosphate

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

Key reference

DOI no: 10.1074/jbc.273.17.10454

J Biol Chem 273:10454-10462 (1998)

PubMed id: 9553104

Visualization of the cysteinyl-phosphate intermediate of a protein-tyrosine phosphatase by x-ray crystallography.

A.D.Pannifer, A.J.Flint, N.K.Tonks, D.Barford.

ABSTRACT

Protein-tyrosine phosphatases (PTPs) are signal transduction enzymes that catalyze the dephosphorylation of phosphotyrosine residues via the formation of a transient cysteinyl-phosphate intermediate. The mechanism of hydrolysis of this intermediate has been examined by generating a Gln-262 --> Ala mutant of PTP1B, which allows the accumulation and trapping of the intermediate within a PTP1B crystal. The structure of the intermediate at 2.5-A resolution reveals that a conformationally flexible loop (the WPD loop) is closed over the entrance to the catalytic site, sequestering the phosphocysteine intermediate and catalytic site water molecules and preventing nonspecific phosphoryltransfer reactions to extraneous phosphoryl acceptors. One of the catalytic site water molecules, the likely nucleophile, forms a hydrogen bond to the putative catalytic base, Asp-181. In the wild-type enzyme, the nucleophilic water molecule would be coordinated by the side chain of Gln-262. In combination with our previous structural data, we can now visualize each of the reaction steps of the PTP catalytic pathway. The hydrolysis of the cysteinyl-phosphate intermediate of PTPs is reminiscent of GTP hydrolysis by the GTPases, in that both families of enzymes utilize an invariant Gln residue to coordinate the attacking nucleophilic water molecule.

Selected figure(s)

Figure 6.
Fig. 6. Stereo views depicting the sequences of the reaction pathway catalyzed by PTP1B. A, PTP1B apoenzyme, with WPD loop open. B, PTP1B C215S Tyr(P)-Michaelis complex, with WPD loop closed; Gln-262 swings out of the catalytic site. C, PTP1B Q262A cysteinyl-phosphate intermediate complex, with WPD loop closed. D, PTP1B vanadate complex, representing the transition state of cysteinyl-phosphate hydrolysis, with WPD loop closed; Gln-262 swings back into the catalytic site. E, PTP1B tungstate-product complex, with WPD loop open.

Figure 7.
Fig. 7. Schematic of the reaction mechanism catalyzed by PTP1B. A, formation of the cysteinyl-phosphate intermediate. B, hydrolysis of the cysteinyl-phosphate intermediate.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (1998, 273, 10454-10462) copyright 1998.

Figures were selected by an automated process.