Pullen Kristi E, Ng Ho-Leung, Sung Pei-Yi, Good Matthew C, Smith Stephen M, Alber Tom
Department of Molecular and Cell Biology, 339 Hildebrand Hall #3206, University of California, Berkeley, Berkeley, CA 94720, USA.
Structure. 2004 Nov;12(11):1947-54. doi: 10.1016/j.str.2004.09.008.
Serine/threonine protein phosphatases are central mediators of phosphorylation-dependent signals in eukaryotes and a variety of pathogenic bacteria. Here, we report the crystal structure of the intracellular catalytic domain of Mycobacterium tuberculosis PstPpp, a membrane-anchored phosphatase in the PP2C family. Despite sharing the fold and two-metal center of human PP2Calpha, the PstPpp catalytic domain binds a third Mn(2+) in a site created by a large shift in a previously unrecognized flap subdomain adjacent to the active site. Mutations in this site selectively increased the Michaelis constant for Mn(2+) in the reaction of a noncognate, small-molecule substrate, p-nitrophenyl phosphate. The PstP/Ppp structure reveals core functional motifs that advance the framework for understanding the mechanisms of substrate recognition, catalysis, and regulation of PP2C phosphatases.
丝氨酸/苏氨酸蛋白磷酸酶是真核生物和多种致病细菌中磷酸化依赖性信号的核心介质。在此，我们报道了结核分枝杆菌PstPpp细胞内催化结构域的晶体结构，PstPpp是PP2C家族中的一种膜锚定磷酸酶。尽管与人类PP2Cα具有相同的折叠结构和双金属中心，但PstPpp催化结构域在与活性位点相邻的一个先前未被识别的侧翼亚结构域发生大幅位移所形成的位点结合了第三个Mn(2+)。该位点的突变选择性地增加了非同源小分子底物对硝基苯磷酸酯反应中Mn(2+)的米氏常数。PstP/Ppp结构揭示了核心功能基序，推进了理解PP2C磷酸酶底物识别、催化和调节机制的框架。
