The arterivirus Nsp4 protease is the prototype of a novel group of chymotrypsin-like enzymes, the 3C-like serine proteases
The arterivirus Nsp4 protease is the prototype of a novel group of chymotrypsin-like enzymes, the 3C-like serine proteases
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DOI：
10.1074/jbc.271.9.4864
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发表时间：
1996-03-01
影响因子：
4.8
通讯作者：
Gorbalenya, AE
中科院分区：
文献类型：
--
作者：
Snijder, EJ;Wassenaar, ALM;Gorbalenya, AE
马动脉炎病毒（一种动脉病毒）的复制酶至少由三种病毒蛋白酶处理。比较序列分析表明，非结构蛋白4 （Nsp4）是一种丝氨酸蛋白酶（SP），它与属于两个不同类群的凝乳胰蛋白酶样酶具有相同的特性。预测SP利用经典凝乳胰蛋白酶样蛋白酶中发现的典型His-Asp-Ser催化三元组。另一方面，其假定的底物结合区含有Thr和His残基，这些残基在病毒3c样半胱氨酸蛋白酶中是保守的，并决定了它们对（Gln/Glu）向下箭头（Gly/Ala/Ser）切割位点的特异性。预测的催化三元组成员（His-1103， Asp-1129和Ser-1184）的替换证实了它们的不可缺少性。Thr-1179和His-1199在底物识别中的作用也得到了诱变结果的支持。发现了一组保守的候选切割位点，与3c样半胱氨酸蛋白酶切割的连接惊人地相似。结果支持复制酶加工模型，其中SP切割多个Glu向下箭头（Gly/Ser/Ala）位点。总的来说，我们的数据将动脉病毒SP描述为一组新的凝乳胰蛋白酶样酶的代表，即3c样丝氨酸蛋白酶。
The replicase of equine arteritis virus, an arterivirus, is processed by at least three viral proteases. Comparative sequence analysis suggested that nonstructural protein 4 (Nsp4) is a serine protease (SP) that shares properties with chymotrypsin-like enzymes belonging to two different groups. The SP was predicted to utilize the canonical His-Asp-Ser catalytic triad found in classical chymotrypsin-like proteases. On the other hand, its putative substrate-binding region contains Thr and His residues, which are conserved in viral 3C-like cysteine proteases and determine their specificity for (Gln/Glu)down arrow(Gly/Ala/Ser) cleavage sites. The replacement of the members of the predicted catalytic triad (His-1103, Asp-1129, and Ser-1184) confirmed their indispensability. The putative role of Thr-1179 and His-1199 in substrate recognition was also supported by the results of mutagenesis. A set of conserved candidate cleavage sites, strikingly similar to junctions cleaved by 3C-like cysteine proteases, was identified. These were tested by mutagenesis and expression of truncated replicase proteins, The results support a replicase processing model in which the SP cleaves multiple Glu down arrow(Gly/Ser/Ala) sites. Collectively, our data characterize the arterivirus SP as a representative of a novel group of chymotrypsin-like enzymes, the 3C-like serine proteases.