Scott D L, Achari A, Vidal J C, Sigler P B
Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637.
J Biol Chem. 1992 Nov 5;267(31):22645-57.
Chemical, genetic, and structural studies have defined a critical role for Asp-49 in the calcium-mediated activation of extracellular phospholipases A2 (PLA2). In 1984, a new class of PLA2 was isolated in which this invariant aspartate was replaced with a lysine (Maragnore, J.M., Merutka, G., Cho, W., Welches, W., Kezdy, F.J., and Heinrikson, R.L. (1984) J. Biol. Chem. 259, 13839-13843; Maragnore, J.M., and Heinrikson, R.L. (1986) J. Biol. Chem. 261, 4797-4804). The enzymatic activity of Lys-49 PLA2s has been questioned based on biochemical, mutational, and structural studies (van den Bergh, C.J., Slotboom, A.J., Verheij, H.M., and de Haas, G.H. (1988) Eur. J. Biochem. 176, 353-357). In this paper, we describe the structures of two crystal forms of the Lys-49 PLA2 isolated from the venom of Agkistridon piscivorus piscivorus. The refined models, along with complementary biochemical analysis, clarify the structural basis for the enzymatic inactivity of Lys-49 proteins.
化学、遗传学和结构研究已确定天冬氨酸-49在细胞外磷脂酶A2（PLA2）的钙介导激活中起关键作用。1984年，分离出一类新的PLA2，其中这个不变的天冬氨酸被赖氨酸取代（Maragnore, J.M., Merutka, G., Cho, W., Welches, W., Kezdy, F.J., and Heinrikson, R.L. (1984) J. Biol. Chem. 259, 13839 - 13843; Maragnore, J.M., and Heinrikson, R.L. (1986) J. Biol. Chem. 261, 4797 - 4804）。基于生化、突变和结构研究，赖氨酸-49 PLA2的酶活性受到质疑（van den Bergh, C.J., Slotboom, A.J., Verheij, H.M., and de Haas, G.H. (1988) Eur. J. Biochem. 176, 353 - 357）。在本文中，我们描述了从食鱼蝮蛇毒液中分离出的赖氨酸-49 PLA2的两种晶体形式的结构。完善后的模型，结合补充的生化分析，阐明了赖氨酸-49蛋白质酶无活性的结构基础。
