Small Molecule Receptor Protein Tyrosine Phosphatase γ (RPTPγ) Ligands That Inhibit Phosphatase Activity via Perturbation of the Tryptophan–Proline–Aspartate (WPD) Loop
作者:Steven Sheriff、Brett R. Beno、Weixu Zhai、Walter A. Kostich、Patricia A. McDonnell、Kevin Kish、Valentina Goldfarb、Mian Gao、Susan E. Kiefer、Joseph Yanchunas、Yanling Huang、Shuhao Shi、Shirong Zhu、Carolyn Dzierba、Joanne Bronson、John E. Macor、Kingsley K. Appiah、Ryan S. Westphal、Jonathan O’Connell、Samuel W. Gerritz
DOI:10.1021/jm2003766
日期:2011.10.13
Protein tyrosine phosphatases (PTPs) catalyze the dephosphorylation of tyrosine residues, a process that involves a conserved tryptophan-proline-aspartate (WPD) loop in catalysis. In previously determined structures of PTPs, the WPD-loop has been observed in either an "open" conformation or a "closed" conformation. In the current work, X-ray structures of the catalytic domain of receptor-like protein tyrosine phosphatase gamma (RPTP gamma) revealed a ligand-induced "superopen" conformation not previously reported for PTPs. In the superopen conformation, the ligand acts as an apparent competitive inhibitor and binds in a small hydrophobic pocket adjacent to, but distinct from, the active site. In the open and closed WPD-loop conformations of RPTP gamma, the side chain of Trp1026 partially occupies this pocket. In the superopen conformation, Trp1026 is displaced allowing a 3,4-dichlorobenzyl substituent to occupy this site. The bound ligand prevents closure of the WPD-loop over the active site and disrupts the catalytic cycle of the enzyme.