STRUCTURE OF ASTACIN AND IMPLICATIONS FOR ACTIVATION OF ASTACINS AND ZINC-LIGATION OF COLLAGENASES
STRUCTURE OF ASTACIN AND IMPLICATIONS FOR ACTIVATION OF ASTACINS AND ZINC-LIGATION OF COLLAGENASES
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DOI：
10.1038/358164a0
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发表时间：
1992-07-09
期刊：
影响因子：
64.8
通讯作者：
STOCKER, W
中科院分区：
文献类型：
--
作者：
BODE, W;GOMISRUTH, FX;STOCKER, W
ASTACIN是来自螯虾Astacus astacus L.的一种锌内肽酶。1，2是“astacin家族”3-5的原型，其包括哺乳动物金属内肽酶5和人6、果蝇7、青蛙8和海胆9，10的发育调节蛋白。在这里，我们报告的X射线晶体结构的astacin，它揭示了一个深的活性位点裂缝，与锌在其底部连接三个组氨酸，水分子和更远程酪氨酸。第三个组氨酸（His 102）形成了一个共有序列的一部分，不仅由astacin家族的成员共享，而且也由其他顺序无关的蛋白酶，如脊椎动物胶原酶11共享。因此，它可能代表了这些酶中难以捉摸的“第三”锌配体。虾青素的氨基末端被掩埋，与Glu 103形成内部盐桥，邻近His 102。在N末端延伸的Astacin前体形式，如观察到的一些“潜伏”的哺乳动物astacin同系物，没有表现出这种“活性”构象，表明激活机制让人想起胰蛋白酶样丝氨酸蛋白酶。
ASTACIN, a digestive zinc-endopeptidase from the crayfish Astacus astacus L. 1,2, is the prototype for the 'astacin family' 3-5, which includes mammalian metallo-endopeptidases 5 and developmentally regulated proteins of man 6, fruitfly 7, frog 8 and sea urchin 9,10. Here we report the X-ray crystal structure of astacin, which reveals a deep active-site cleft, with the zinc at its bottom ligated by three histidines, a water molecule and a more remote tyrosine. The third histidine (His 102) forms part of a consensus sequence, shared not only by the members of the astacin family, but also by otherwise sequentially unrelated proteinases, such as vertebrate collagenases 11. It may therefore represent the elusive 'third' zinc ligand in these enzymes. The amino terminus of astacin is buried forming an internal salt-bridge with Glu 103, adjacent to His 102. Astacin pro-forms extended at the N terminus, as observed for some 'latent' mammalian astacin homologues, did not exhibit this 'active' conformation, indicating an activation mechanism reminiscent of trypsin-like serine proteinases.