Thermosensitive mutants of the MPTP and hPTP1B protein tyrosine phosphatases: isolation and structural analysis.
A PCR-based random mutagenesis procedure was employed to identify several thermosensitive mutants of the MPTP enzyme, the murine homologue of the human T-cell PTPase and rat PTP-S enzymes. Four mutants with varying degrees of thermosensitivity were characterized for their thermostability and refolding properties following incubation at the nonpermissive temperature. Structure analysis of these mutations based on the hPTP1B co-ordinate structure demonstrates a clear relationship between the position of each mutated amino acid relative to the catalytic cysteine residue and their thermostability. Introduction of two of these mutations in the related enzyme hPTP1B suggests that the structural defects and the resulting thermosensitivity of these mutations may represent an intrinsic property of all PTPase catalytic domains.
Muise
E S
ES
Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
Vrielink
A
A
Ennis
M A
MA
Lemieux
N H
NH
Tremblay
M L
ML
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004795:Enzyme Stability; D006358:Hot Temperature; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009113:Muramidase / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D009596:Nitrophenols / Q000378:metabolism; D009838:Oligodeoxyribonucleotides; D009943:Organophosphorus Compounds / Q000378:metabolism; D054578:Protein Tyrosine Phosphatase, Non-Receptor Type 2; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000302:isolation & purification; D051381:Rats; D013379:Substrate Specificity
D009596:Nitrophenols; D009838:Oligodeoxyribonucleotides; D009943:Organophosphorus Compounds; C008644:nitrophenylphosphate; C516649:PTPN2 protein, human; D054578:Protein Tyrosine Phosphatase, Non-Receptor Type 2; D017027:Protein Tyrosine Phosphatases; C516653:Ptpn2 protein, mouse; C516654:Ptpn2 protein, rat; D009113:Muramidase