Molecular basis for P-site inhibition of adenylyl cyclase.
Molecular basis for P-site inhibition of adenylyl cyclase.
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DOI：
10.1021/bi0015562
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发表时间：
2000-11
期刊：
影响因子：
2.9
通讯作者：
J. Tesmer;C. Dessauer;R. Sunahara;L. Murray;Roger A. Johnson;A. G. Gilman;S. Sprang
中科院分区：
文献类型：
--
作者：
J. Tesmer;C. Dessauer;R. Sunahara;L. Murray;Roger A. Johnson;A. G. Gilman;S. Sprang
P位点抑制剂是腺苷和腺嘌呤核苷酸类似物，其抑制腺苷酸环化酶，腺苷酸环化酶是催化ATP合成环AMP的效应酶。这些抑制剂中的一些可能代表腺苷酸环化酶的生理调节剂，并且最有效的可能最终用作有用的治疗剂。本文描述了腺苷酸环化酶的催化核心与两种这样的P位点抑制剂2 ′-脱氧腺苷3 ′-单磷酸（2 ′-d-3 ′-AMP）和2 ′，5 ′-二脱氧腺苷3 ′-三磷酸（2 ′，5 ′-dd-3 ′-ATP）复合的晶体结构。这两种抑制剂结合在活性位点，但表现出非竞争性或非竞争性的抑制模式。虽然大多数P位点抑制剂需要焦磷酸盐（PP（i））作为共抑制剂，但2 '，5'-dd-3 '-ATP本身是有效的抑制剂。晶体结构显示，该抑制剂表现出两种结合模式：一种是核苷部分与酶的核苷结合口袋结合，另一种是β和γ磷酸与2 ′-d-3 ′-AMP.PP（i）复合物的焦磷酸位点结合。在与2 ′-d-3 ′-AMP的复合物中观察到单个金属结合位点，而在与2 ′，5 ′-dd-3 ′-ATP的复合物中观察到两个金属结合位点。尽管P-位点抑制剂在Mn（2+）存在下通常是10倍更有效，但电子密度图显示Mn（2+）对Mg（2+）的任一金属位点没有固有的偏好。2 '，5'-dd-3 '-ATP与腺苷酸环化酶的催化核心结合，在Mg（2+）存在下K（d）为2.4 μ M，在Mn（2+）存在下K（d）为0.2 μ M。焦磷酸盐不与2 '，5'-dd-3 '-ATP竞争并增强抑制。
P-site inhibitors are adenosine and adenine nucleotide analogues that inhibit adenylyl cyclase, the effector enzyme that catalyzes the synthesis of cyclic AMP from ATP. Some of these inhibitors may represent physiological regulators of adenylyl cyclase, and the most potent may ultimately serve as useful therapeutic agents. Described here are crystal structures of the catalytic core of adenylyl cyclase complexed with two such P-site inhibitors, 2'-deoxyadenosine 3'-monophosphate (2'-d-3'-AMP) and 2',5'-dideoxyadenosine 3'-triphosphate (2',5'-dd-3'-ATP). Both inhibitors bind in the active site yet exhibit non- or uncompetitive patterns of inhibition. While most P-site inhibitors require pyrophosphate (PP(i)) as a coinhibitor, 2',5'-dd-3'-ATP is a potent inhibitor by itself. The crystal structure reveals that this inhibitor exhibits two binding modes: one with the nucleoside moiety bound to the nucleoside binding pocket of the enzyme and the other with the beta and gamma phosphates bound to the pyrophosphate site of the 2'-d-3'-AMP.PP(i) complex. A single metal binding site is observed in the complex with 2'-d-3'-AMP, whereas two are observed in the complex with 2', 5'-dd-3'-ATP. Even though P-site inhibitors are typically 10 times more potent in the presence of Mn(2+), the electron density maps reveal no inherent preference of either metal site for Mn(2+) over Mg(2+). 2',5'-dd-3'-ATP binds to the catalytic core of adenylyl cyclase with a K(d) of 2.4 microM in the presence of Mg(2+) and 0.2 microM in the presence of Mn(2+). Pyrophosphate does not compete with 2',5'-dd-3'-ATP and enhances inhibition.