PDBsum entry 1zc0

Hydrolase

PDB id

1zc0

Contents

			Protein chain

					286 a.a.

			Ligands

					PO4

			Waters ×286

References listed in PDB file

Key reference

Title

Structure of the hematopoietic tyrosine phosphatase (heptp) catalytic domain: structure of a kim phosphatase with phosphate bound at the active site.

Authors

T.Mustelin, L.Tautz, R.Page.

Ref.

J Mol Biol, 2005, 354, 150-163. [DOI no: 10.1016/j.jmb.2005.09.049]

PubMed id

16226275

Abstract

Hematopoietic tyrosine phosphatase (HePTP) is a 38kDa class I non-receptor protein tyrosine phosphatase (PTP) that is strongly expressed in T cells. It is composed of a C-terminal classical PTP domain (residues 44-339) and a short N-terminal extension (residues 1-43) that functions to direct HePTP to its physiological substrates. Moreover, HePTP is a member of a recently identified family of PTPs that has a major role in regulating the activity and translocation of the MAP kinases Erk and p38. HePTP binds Erk and p38 via a short, highly conserved motif in its N terminus, termed the kinase interaction motif (KIM). Association of HePTP with Erk via the KIM results in an unusual, reciprocal interaction between the two proteins. First, Erk phosphorylates HePTP at residues Thr45 and Ser72. Second, HePTP dephosphorylates Erk at PTyr185. In order to gain further insight into the interaction of HePTP with Erk, we determined the structure of the PTP catalytic domain of HePTP, residues 44-339. The HePTP catalytic phosphatase domain displays the classical PTP1B fold and superimposes well with PTP-SL, the first KIM-containing phosphatase solved to high resolution. In contrast to the PTP-SL structure, however, HePTP crystallized with a well-ordered phosphate ion bound at the active site. This resulted in the closure of the catalytically important WPD loop, and thus, HePTP represents the first KIM-containing phosphatase solved in the closed conformation. Finally, using this structure of the HePTP catalytic domain, we show that both the phosphorylation of HePTP at Thr45 and Ser72 by Erk2 and the dephosphorylation of Erk2 at Tyr185 by HePTP require significant conformational changes in both proteins.



	Figure 1. Figure 1. Cartoon representation and structure of HePTP. (a) Cartoon representation of HePTP domain structure. The N-terminal domain of HePTP (cyan) includes the kinase interaction motif (KIM, pink, residues 15-30) while the C-terminal domain includes the PTP domain (orange, residues 44-339). The HePTP domain solved to high resolution is that of the PTP catalytic domain (residues 44-339). (b) Secondary structure of HePTP catalytic domain. Secondary structure elements numbered as for PTP1B. The bound phosphate ion is shown as a space-filling model in red. Four residues of the loop connecting b-strand 4 to b-strand 7 (b-strands 5 and 6 are not present in HePTP) could not be modeled and are presumably disordered. (c) PTP motifs in HePTP. The HePTP WPD loop is shown in cyan, the PTP motif phosphate-binding loop in magenta, the Q-loop in green and a-helix a0 in coral.21		Figure 2. Figure 2. The HePTP active site. (a) Electron density for the bound phosphate moiety. Magenta, sA-weighted 2mF[o] -DF[c] map contoured at 1.5s; red, sA-weighted mF[o] -DF[c] omit map contoured at 4.5s. Electron density maps clearly illustrate the tetrahedral-shaped density of the phosphate ion. (b) Reorientation of the WPD loop upon phosphate binding. The superposition of the active site of HePTP (orange) and apo-PTP-SL (blue) is shown. The binding of the phosphate ion leads to the rotation of the Arg276 side-chain about the Cg atom, the closing of the WPD loop and the subsequent reorientation of the catalytic acid Asp236 in HePTP relative to PTP-SL. The HePTP and PTP-SL structures have been superimposed over 253 residues with an rmsd of 0.72 Å. (c) Dual conformations of active site residues His237 and Gln314. The hydrogen bonding network of the bound phosphate ion is shown. Residues from the WPD loop (purple), PTP motif phosphate-binding loop (coral) and Q-loop (cyan) interact with the bound phosphate. Water molecules are shown as stars. The dual conformations of His237 (WPD loop) and Gln314 (Q loop) are shown.

PROCHECK

	Headers