Mechanistic studies of phosphoserine phosphatase, an enzyme related to P-type ATPases

作     者：Collet, JF Stroobant, V Van Schaftingen, E 

作者机构：Christian de Duve Inst Cellular Pathol Chim Physiol Lab B-1200 Brussels Belgium Catholic Univ Louvain B-1200 Brussels Belgium Ludwig Inst Canc Res B-1200 Brussels Belgium 

出 版 物：《JOURNAL OF BIOLOGICAL CHEMISTRY》 (生物化学杂志)

年 卷 期：1999年第274卷第48期

页      面：33985-33990页

核心收录：

学科分类：0710[理学-生物学] 071010[理学-生物化学与分子生物学] 07[理学] 

主　　题：腺苷三磷酸酶类/化学 腺苷三磷酸酶类/遗传学 腺苷三磷酸酶类/代谢 氨基酸序列 氨基酸取代 天冬氨酸/代谢 氢硼化物/药理学 催化作用 氢离子浓度 水解作用 动力学 质谱分析法/方法 诱变 定点 氧化还原/药物作用 氧同位素 磷蛋白类/代谢 磷酸单酯水解酶类/化学 磷酸单酯水解酶类/遗传学 磷酸单酯水解酶类/代谢 磷酰化 重组蛋白质类/化学 重组蛋白质类/遗传学 重组蛋白质类/代谢 序列同源性 氨基酸 胰蛋白酶/代谢 水/代谢 人类 

摘      要：Phosphoserine phosphatase belongs to a new class of phosphotransferases forming an acylphosphate during catalysis and sharing three motifs with P-type ATPases and haloacid dehalogenases, The phosphorylated residue was identified as the first aspartate in the first motif (DXDXT) by mass spectrometry analysis of peptides derived from the phosphorylated enzyme treated with NaBH4 or alkaline [O-18]H2O. Incubation of native phosphoserine phosphatase with phosphoserine in [O-18]H2O did not result in O-18 incorporation in residue Asp-20, indicating that the phosphoaspartate is hydrolyzed, as in P-type ATPases, by attack of the phosphorus atom. Mutagenesis studies bearing on conserved residues indicated that four conservative changes either did not affect (S109T) or caused a moderate decrease in activity (G178A, D179E, and D183E), Other mutations inactivated the enzyme by 80% (S109A and G180A) or even by greater than or equal to 99% (D179N, D183N, K158A, and K158R), Mutations G178A and D179N decreased the affinity for phosphoserine, suggesting that these residues participate in the binding of the substrate. Mutations of Asp-179 decreased the affinity for Mg2+, indicating that this residue interacts with the cation, Thus, investigated residues appear to play an important role in the reaction mechanism of phosphoserine phosphatase, as is known for equivalent residues in P-type ATPases and haloacid dehalogenases.