Structural Basis for Substrate Specificity of Protein-tyrosine Phosphatase SHP-1

Crystal structures of protein-tyrosine phosphatase 1B in complex with compounds bearing a novel isothiazolidinone (IZD) heterocyclic phosphonate mimetic reveal that the heterocycle is highly complementary to the catalytic pocket of the protein. The heterocycle participates in an extensive network of hydrogen bonds with the backbone of the phosphate-binding loop, Phe182 of the flap, and the side chain of Arg221. When substituted with a phenol, the small inhibitor induces the closed conformation of the protein and displaces all waters in the catalytic pocket. Saturated IZD-containing peptides are more potent inhibitors than unsaturated analogs because the IZD heterocycle and phenyl ring directly attached to it bind in a nearly orthogonal orientation with respect to each other, a conformation that is close to the energy minimum of the saturated IZD-phenyl moiety. These results explain why the heterocycle is a potent phosphonate mimetic and an ideal starting point for designing small nonpeptidic inhibitors.

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The Molecular Basis for the Substrate Specificity of Protein Tyrosine Phosphatase PTPN3

Structure ◽

10.1016/j.str.2015.03.005 ◽

2015 ◽

Vol 23 (4) ◽

pp. 608-609 ◽

Cited By ~ 5

Author(s):

Emily J. Parker

Keyword(s):

Substrate Specificity ◽

Protein Tyrosine Phosphatase ◽

Molecular Basis ◽

Tyrosine Phosphatase ◽

Protein Tyrosine

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Molecular Determinants of Substrate Recognition in Hematopoietic Protein-tyrosine Phosphatase

Journal of Biological Chemistry ◽

10.1074/jbc.m407820200 ◽

2004 ◽

Vol 279 (50) ◽

pp. 52150-52159 ◽

Cited By ~ 19

Author(s):

Zhonghui Huang ◽

Bo Zhou ◽

Zhong-Yin Zhang

Keyword(s):

Substrate Specificity ◽

Protein Tyrosine Phosphatase ◽

Cellular Proliferation ◽

High Efficiency ◽

Tyrosine Phosphatase ◽

Substrate Recognition ◽

Fold Increase ◽

Phosphoryl Transfer ◽

Protein Tyrosine ◽

Hydrolysis Of

The extracellular signal-regulated protein kinase 2 (ERK2) plays a central role in cellular proliferation and differentiation. Full activation of ERK2 requires dual phosphorylation of Thr183and Tyr185in the activation loop. Tyr185dephosphorylation by the hematopoietic protein-tyrosine phosphatase (HePTP) represents an important mechanism for down-regulating ERK2 activity. The bisphosphorylated ERK2 is a highly efficient substrate for HePTP with akcat/Kmof 2.6 × 106m–1s–1. In contrast, thekcatK/mvalues for the HePTP-catalyzed hydrolysis of Tyr(P) peptides are 3 orders of magnitude lower. To gain insight into the molecular basis for HePTP substrate specificity, we analyzed the effects of altering structural features unique to HePTP on the HePTP-catalyzed hydrolysis ofp-nitrophenyl phosphate, Tyr(P) peptides, and its physiological substrate ERK2. Our results suggest that substrate specificity is conferred upon HePTP by both negative and positive selections. To avoid nonspecific tyrosine dephosphorylation, HePTP employs Thr106in the substrate recognition loop as a key negative determinant to restrain its protein-tyrosine phosphatase activity. The extremely high efficiency and fidelity of ERK2 dephosphorylation by HePTP is achieved by a bipartite protein-protein interaction mechanism, in which docking interactions between the kinase interaction motif in HePTP and the common docking site in ERK2 promote the HePTP-catalyzed ERK2 dephosphorylation (∼20-fold increase inkcat/Km) by increasing the local substrate concentration, and second site interactions between the HePTP catalytic site and the ERK2 substrate-binding region enhance catalysis (∼20-fold increase inkcat/Km) by organizing the catalytic residues with respect to Tyr(P)185for optimal phosphoryl transfer.

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