4QBW

The second sphere residue T263 is important for function and activity of PTP1B through modulating WPD loop

Summary for 4QBW

• Entry DOI: 10.2210/pdb4qbw/pdb
• Related: 4QAH 4QAP 4QBE
• Descriptor: Tyrosine-protein phosphatase non-receptor type 1, 2-AMINO-2-HYDROXYMETHYL-PROPANE-1,3-DIOL (3 entities in total)
• Functional Keywords: tyrosine phosphorylation, classic ptyr-specific ptp, hydrolase
• Biological source: Homo sapiens (human)
• Cellular location: Endoplasmic reticulum membrane ; Peripheral membrane protein ; Cytoplasmic side : P18031
• Total number of polymer chains: 1
• Total formula weight: 34955.87

Authors

Xiao, P.,Wang, X.,Wang, H.M.,Fu, X.L.,Cui, F.A.,Yu, X.,Bi, W.X.,Sun, J.P. (deposition date: 2014-05-08, release date: 2015-02-11, Last modification date: 2024-03-20)

Primary citation

Xiao, P.,Wang, X.,Wang, H.M.,Fu, X.L.,Cui, F.A.,Yu, X.,Wen, S.S.,Bi, W.X.,Sun, J.P.
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, 2014

PubMed 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.

PubMed: 25450460
DOI: 10.1016/j.biocel.2014.10.004

Experimental method

X-RAY DIFFRACTION (1.912 Å)