PDBsum entry 4qbw

Hydrolase

PDB id: 4qbw

Contents

Protein chain

299 a.a.

Ligands

TRS

Waters ×130

PDB id:

4qbw

Name:

Hydrolase

Title:

The second sphere residue t263 is important for function and activity of ptp1b through modulating wpd loop

Structure:

Tyrosine-protein phosphatase non-receptor type 1. Chain: a. Fragment: unp residues 1-299. Synonym: protein-tyrosine phosphatase 1b, ptp-1b. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: ptpn1, ptp1b. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.91Å R-factor: 0.208 R-free: 0.239

Authors:

P.Xiao,X.Wang,H.M.Wang,X.L.Fu,F.A.Cui,X.Yu,W.X.Bi,J.P.Sun

Key ref:

P.Xiao et al. (2014). The second-sphere residue T263 is important for the function and catalytic activity of PTP1B via interaction with the WPD-loop. Int J Biochem Cell Biol, 57, 84-95. PubMed id: 25450460 DOI: 10.1016/j.biocel.2014.10.004

Date:

08-May-14 Release date: 11-Feb-15

Protein chain

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

Seq: 435 a.a.

Struc: 299 a.a.

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: 10.1016/j.biocel.2014.10.004

Int J Biochem Cell Biol 57:84-95 (2014)

PubMed id: 25450460

The second-sphere residue T263 is important for the function and catalytic activity of PTP1B via interaction with the WPD-loop.

P.Xiao, X.Wang, H.M.Wang, X.L.Fu, F.A.Cui, X.Yu, S.S.Wen, W.X.Bi, J.P.Sun.

ABSTRACT

Protein tyrosine phosphatases have diverse substrate specificities and intrinsic activities that lay the foundations for the fine-tuning of a phosphorylation network to precisely regulate cellular signal transduction. All classical PTPs share common catalytic mechanisms, and the important catalytic residues in the first sphere of their active sites have been well characterized. However, little attention has been paid to the second-sphere residues that are potentially important in defining the intrinsic activity and substrate specificity of PTPs. Here, we find that a conserved second-sphere residue, Thr263, located in the surface Q-loop is important for both the function and activity of PTPs. Using PTP1B as a study model, we found that mutations of Thr263 impaired the negative regulation role of PTP1B in insulin signaling. A detailed mechanistic study utilizing steady-state kinetics, Brønsted analysis and pH dependence in the presence of pNPP or phosphopeptide substrates revealed that Thr263 is required for the stabilization of the leaving group during catalysis. Further crystallographic studies and structural comparison revealed that Thr263 regulates the general acid function through modulation of the WPD-loop by the T263:F182/Y/H interaction pair, which is conserved in 26 out of 32 classical PTPs. In addition, the hydrophobic interaction between Thr263 and Arg1159 of the insulin receptor contributes to the substrate specificity of PTP1B. Taken together, our findings demonstrate the general role of the second-sphere residue Thr263 in PTP catalysis. Our findings suggest that the second sphere residues of PTP active site may play important roles in PTP-mediated function in both normal and diseased states.