Visualizing transient events in amino-terminal autoprocessing of HIV-1 protease.
Visualizing transient events in amino-terminal autoprocessing of HIV-1 protease.
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DOI：
10.1038/nature07342
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发表时间：
2008-10-02
期刊：
影响因子：
64.8
通讯作者：
Clore, G. Marius
中科院分区：
文献类型：
--
作者：
Tang, Chun;Louis, John M.;Aniana, Annie;Suh, Jeong-Yong;Clore, G. Marius
HIV-1蛋白酶将Gag和Gag-Pol多聚蛋白加工成成熟的结构和功能蛋白，包括其自身，因此对于病毒成熟是必不可少的。成熟蛋白酶仅作为二聚体具有活性，其中每个亚基贡献催化残基。全长跨框区蛋白酶前体似乎是单体的，但通过推定的前体二聚体的分子内裂解经历成熟，伴随着成熟样催化活性的出现。当成熟蛋白酶的氨基和羧基末端是位于活性位点远端的亚基间β折叠的一部分时，这种分子内切割如何发生尚不清楚。在这里，我们可视化的早期事件在N-末端自动处理使用一个无活性的迷你前体与四个残基的N-末端延伸，模仿transframe区域蛋白酶前体。使用顺磁弛豫增强，一种技术，这是精致的存在下的次要物种敏感，我们表明，迷你前体形式高度瞬态，低人口（3-5%）二聚体遇到复杂的涉及成熟的二聚体界面，但占据了广泛的亚基取向相对于成熟的二聚体。此外，成熟二聚体构型的占据构成了自缔合物种的非常小的一部分（占蛋白酶前体的非常低的酶活性），并且N-末端延伸使瞬时亚基内和亚基间与底物结合位点接触，因此当在相遇复合物系综内采样正确的二聚体取向时，可用于自裂解。
HIV-1 protease processes the Gag and Gag-Pol polyproteins into mature structural and functional proteins, including itself, and is therefore indispensable for viral maturation. The mature protease is active only as a dimer with each subunit contributing catalytic residues. The full-length transframe region protease precursor appears to be monomeric yet undergoes maturation via intramolecular cleavage of a putative precursor dimer, concomitant with the appearance of mature-like catalytic activity. How such intramolecular cleavage can occur when the amino and carboxy termini of the mature protease are part of an intersubunit β-sheet located distal from the active site is unclear. Here we visualize the early events in N-terminal autoprocessing using an inactive mini-precursor with a four-residue N-terminal extension that mimics the transframe region protease precursor. Using paramagnetic relaxation enhancement, a technique that is exquisitely sensitive to the presence of minor species, we show that the mini-precursor forms highly transient, lowly populated (3–5%) dimeric encounter complexes that involve the mature dimer interface but occupy a wide range of subunit orientations relative to the mature dimer. Furthermore, the occupancy of the mature dimer configuration constitutes a very small fraction of the self-associated species (accounting for the very low enzymatic activity of the protease precursor), and the N-terminal extension makes transient intra- and intersubunit contacts with the substrate binding site and is therefore available for autocleavage when the correct dimer orientation is sampled within the encounter complex ensemble.
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影响因子：
2.7
作者：
Chou, JJ;Baber, JL;Bax, A
通讯作者：
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DOI：
10.1073/pnas.0800256105
发表时间：
2008-03-25
影响因子：
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DOI：
10.1073/pnas.91.17.7970
发表时间：
1994-08-16
影响因子：
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作者：
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通讯作者：
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