期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 105, 期 19, 页码 6882-6887出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0802535105
关键词
ATP hydrolysis; CD39-like; ecto-enzyme; membrane protein; x-ray structure
Cell surface-located nucleoside triphosphate diphosphohydrolases (NTPDase1, -2, -3, and -8) are oligomeric integral membrane proteins responsible for signal conversion and inactivation in extracellular nucleotide-mediated purinergic signaling. They catalyze the sequential hydrolysis of the signaling molecule ATP via ADP to AMP. Here we present the structure of the extracellular domain of Rattus norvegicus NTPDase2 in an active state at resolutions between 1.7 angstrom and 2.1 angstrom in four different forms: (i) apo form, (ii) ternary complex with the nonhydrolyzable ATP analog AMPPNP and cofactor Ca2+, (fit) quaternary complex with Ca2+ and bound products AMP and phosphate, and (iv) binary product complex with AMP only. Analysis of the ATP (analog) binding mode explains the importance of several residues for activity and allows suggestion of a catalytic mechanism. The carboxylate group of E165 serves as a catalytic base and activates a water molecule, which is well positioned for nucleophilic attack on the terminal phosphate. Based on analysis of the two product complex structures in which AMP adopts different conformations, a substrate binding mode for ADP hydrolysis is proposed. This allows for an understanding of how the same hydrolytic site can be engaged in ATP and ADP but not AMP hydrolysis.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据