PDBsum entry 1i57

Hydrolase

PDB id: 1i57

Contents

Protein chain

284 a.a. *

Metals

_CL ×5

_MG

Waters ×250

* Residue conservation analysis

PDB id:

1i57

Name:

Hydrolase

Title:

Crystal structure of apo human ptp1b (c215s) mutant

Structure:

Phospho-tyrosine phosphatase 1b. Chain: a. Fragment: catalytic domain (1-298). Synonym: ptp-1b, protein-tyrosine phosphatase, non-receptor type 1, protein-tyrosine phosphatase 1b. Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: ptn1_human. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Biol. unit:

Dimer (from PQS)

Resolution:

2.10Å R-factor: 0.195 R-free: 0.266

Authors:

G.Scapin,S.Patel,V.Patel,B.Kennedy,E.Asante-Appiah

Key ref:

G.Scapin et al. (2001). The structure of apo protein-tyrosine phosphatase 1B C215S mutant: more than just an S --> O change. Protein Sci, 10, 1596-1605. PubMed id: 11468356

Date:

26-Feb-01 Release date: 08-Aug-01

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 1 residue position (black cross)

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

Protein Sci 10:1596-1605 (2001)

PubMed id: 11468356

The structure of apo protein-tyrosine phosphatase 1B C215S mutant: more than just an S --> O change.

G.Scapin, S.Patel, V.Patel, B.Kennedy, E.Asante-Appiah.

ABSTRACT

Protein-tyrosine phosphatases catalyze the hydrolysis of phosphate monoesters via a two-step mechanism involving a covalent phospho-enzyme intermediate. Biochemical and site-directed mutagenesis experiments show that the invariant Cys residue present in the PTPase signature motif (H/V)CX(5)R(S/T) (i.e., C215 in PTP1B) is absolutely required for activity. Mutation of the invariant Cys to Ser results in a catalytically inactive enzyme, which still is capable of binding substrates and inhibitors. Although it often is assumed that substrate-trapping mutants such as the C215S retain, in solution, the structural and binding properties of wild-type PTPases, significant differences have been found in the few studies that have addressed this issue, suggesting that the mutation may lead to structural/conformational alterations in or near the PTP1B binding site. Several crystal structures of apo-WT PTP1B, and of WT- and C215S-mutant PTP1B in complex with different ligands are available, but no structure of the apo-PTP1B C215S has ever been reported. In all previously reported structures, residues of the PTPase signature motif have an identical conformation, while residues of the WPD loop (a surface loop which includes the catalytic Asp) assume a different conformation in the presence or absence of ligand. These observations led to the hypothesis that the different spectroscopic and thermodynamic properties of the mutant protein may be the result of a different conformation for the WPD loop. We report here the structure of the apo-PTP1B C215S mutant, which reveals that, while the WPD loop is in the open conformation observed in the apo WT enzyme crystal structure, the residues of the PTPases signature motif are in a dramatically different conformation. These results provide a structural basis for the differences in spectroscopic properties and thermodynamic parameters in inhibitor binding observed for the wild-type and mutant enzymes.