PDBsum entry 3i7z

Hydrolase

PDB id: 3i7z

Contents

Protein chain

297 a.a.

Ligands

ASP-ALA-ASP-GLU-TYR-LEU

VO4

TRS ×2

GOL ×2

Waters ×150

References listed in PDB file

Key reference

• Title: Insights into the reaction of protein-Tyrosine phosphatase 1b: crystal structures for transition state analogs of both catalytic steps.
• Authors: T.A.Brandão, A.C.Hengge, S.J.Johnson.
• Ref.: J Biol Chem, 2010, 285, 15874-15883.
• PubMed id: 20236928

Abstract

Catalysis by protein-tyrosine phosphatase 1B (PTP1B) occurs through a two-step mechanism involving a phosphocysteine intermediate. We have solved crystal structures for the transition state analogs for both steps. Together with previously reported crystal structures of apo-PTP1B, the Michaelis complex of an inactive mutant, the phosphoenzyme intermediate, and the product complex, a full picture of all catalytic steps can now be depicted. The transition state analog for the first catalytic step comprises a ternary complex between the catalytic cysteine of PTP1B, vanadate, and the peptide DADEYL, a fragment of a physiological substrate. The equatorial vanadate oxygen atoms bind to the P-loop, and the apical positions are occupied by the peptide tyrosine oxygen and by the PTP1B cysteine sulfur atom. The vanadate assumes a trigonal bipyramidal geometry in both transition state analog structures, with very similar apical O-O distances, denoting similar transition states for both phosphoryl transfer steps. Detailed interactions between the flanking peptide and the enzyme are discussed.