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Identification of an essential acidic residue in Cdc25 protein phosphatase and a general three‐dimensional model for a core region in protein phosphatases
Author(s) -
Eckstein Jens W.,
BeerRomero Peggy,
Berdo Ingrid
Publication year - 1996
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560050102
Subject(s) - phosphatase , cdc25 , residue (chemistry) , biochemistry , chemistry , protein phosphatase 2 , protein phosphatase 1 , enzyme , cell , cell cycle , cyclin dependent kinase 1
The reaction mechanism of protein tyrosine phosphatases (PTPases) and dual‐specificity protein phosphatases is thought to involve a catalytic aspartic acid residue. This residue was recently identified by site‐directed mutagenesis in Yersinia PTPase , VHR protein phosphatase, and bovine low molecular weight protein phosphatase. Herein we identify aspartic acid 383 as a potential candidate for the catalytic acid in human Cdc25A protein phosphatase, using sequence alignment, structural information, and site‐directed mutagenesis. The D383N mutant enzyme exhibits a 150‐fold reduction in k cat , with K m only slightly changed. Analysis of sequence homologies between several members of the Cdc25 family and deletion mutagenesis substantiate the concept of a two‐domain structure for Cdc25, with a regulatory N‐terminal and a catalytic C‐terminal domain. Based on the alignment of catalytic residues and secondary structure elements, we present a three‐dimensional model for the core region of Cdc25. By comparing this three‐dimensional model to the crystal structures of PTP1b, Yersinia PTPase , and bovine low molecular weight PTPase, which share only very limited amino acid sequence similarities, we identify a general architecture of the protein phosphatase core region, encompassing the active site loop motif HCR and the catalytic aspartic acid residue.