structural stability of human protein tyrosine phosphatase ρ catalytic domain effect of point mutations结构稳定性的人类蛋白质酪氨酸磷酸酶ρ催化域点突变的影响.pdfVIP

Structural Stability of Human Protein Tyrosine Phosphatase r Catalytic Domain: Effect of Point Mutations 1. 2. 3 3 2 Alessandra Pasquo , Valerio Consalvi , Stefan Knapp , Ivan Alfano , Matteo Ardini , Simonetta 2 2 Stefanini , Roberta Chiaraluce * 1 UT-BIORAD-FARM CR Casaccia ENEA, Rome, Italy, 2 Department of Biochemical Sciences ‘‘A. Rossi Fanelli’’, Sapienza University of Rome, Rome, Italy, 3 Structural Genomics Consortium, Oxford University, Oxford, England, United Kingdom Abstract Protein tyrosine phosphatase r (PTPr) belongs to the classical receptor type IIB family of protein tyrosine phosphatase, the most frequently mutated tyrosine phosphatase in human cancer. There are evidences to suggest that PTPr may act as a tumor suppressor gene and dysregulation of Tyr phosphorylation can be observed in diverse diseases, such as diabetes, immune deficiencies and cancer. PTPr variants in the catalytic domain have been identified in cancer tissues. These natural variants are nonsynonymous single nucleotide polymorphisms, variations of a single nucleotide occurring in the coding region and leading to amino acid substitutions. In this study we investigated the effect of amino acid substitution on the structural stability and on the activity of the membrane-proximal catalytic domain of PTPr. We expressed and purified as soluble recombinant proteins some of the mutants of the membrane-proximal catalytic domain of PTPr identified in colorectal cancer and in the single nucleotide polymorphisms database. The mutants show a decreased thermal and thermodynamic stability and decreased activation energy relative to phosphatase activity, when compared