A DETAILED KINETIC-ANALYSIS OF THE INVITRO SYNTHESIS AND PROCESSING OF ENCEPHALOMYOCARDITIS VIRUS PRODUCTS
A DETAILED KINETIC-ANALYSIS OF THE INVITRO SYNTHESIS AND PROCESSING OF ENCEPHALOMYOCARDITIS VIRUS PRODUCTS
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DOI：
10.1016/0042-6822(86)90092-9
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发表时间：
1986-02-01
期刊：
影响因子：
3.7
通讯作者：
JACKSON, RJ
中科院分区：
文献类型：
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作者：
JACKSON, RJ
脑心肌炎病毒RNA在兔网织红细胞裂解物中的翻译被用来分析初级翻译产物的蛋白分解加工途径。至少需要两种不同的蛋白酶来解释结果：一种是从新生多蛋白中切除衣壳前体蛋白A1，另一种是包括F/C连接处的切割在内的所有其他切割。A1的切割是一个极快的反应，一旦切割位点被合成就会发生，并且对所有测试的蛋白降解抑制剂和高温都具有抵抗力，这些特征更符合由病毒编码的蛋白酶催化的分子内切割，而不是由内源性网织红细胞蛋白酶催化的切割。一旦切除，A1保持稳定，直到翻译到达基因组编码C的区域的中间，此时快速连续发生许多事件：(I)F可能通过分子内切割以其成熟的形式被切除；(Ii)能够将A1二次加工为A、B、D1、α、伽马的蛋白分解活性。还有.埃西隆。出现；和(Iii)出现一种分子量约为32,000的多肽。这种蛋白(P32)起源于C的N端部分，并与p22位于基因组上相同的位置，该蛋白以前被鉴定为病毒编码的蛋白酶。多肽p32是由C通过一步裂解产生E作为另一种产物，一条加工途径至少与通过D作为中间体的逐步路线同样重要，如果不是更重要的话。由于p32第一次出现与二次加工的开始同时出现，而p22第一次被检测到的时间要晚得多，因此有人认为，至少衣壳前体的加工的早期阶段必须是由p32而不是p22进行的。
Translation of encephalomyocarditis virus RNA in rabbit reticulocyte lysates has been used to analyse the pathway of proteolytic processing of the primary translation products. A minimum of two distinct proteases is required to account for the results: one for the excision of the capsid precursor protein, A1, from the nascent polyprotein, and the other for all other cleavages including cleavage at the F/C junction. The excision of A1 is an extremely rapid reaction which occurs as soon as the cleavage site has been synthesized and is resistant to all the proteolytic inhibitors tested and to high temperature, characteristics which are more consistent with an intramolecular cleavage catalysed by a virus-coded protease than cleavage by an endogenous reticulocyte protease. Once excised, A1 remains stable until translation has reached the middle of the region of the genome coding for C, at which time a number of events occur in rapid succession: (i) F is excised in its mature form probably via an intramolecular cleavage; (ii) a proteolytic activity capable of secondary processing of A1 to A, B, D1, .alpha., .gamma. and .epsilon. appears; and (iii) a polypeptide of molecular weight about 32,000 appears. This protein (p32) originates from the N-terminal portion of C, and maps in the same position on the genome as p22, the protein previously identified as the virus-coded protease. Polypeptide p32 is derived from C by a single step cleavage generating E as the other product, a processing pathway at least as important, if not more important than the step-wise route via D as an intermediate. Since p32 first appeared at the same time as the start of secondary processing, whilst p22 was first detected much later, it is argued that at least the early stages of processing of the capsid precursor must have been carried out by p32 rather than p22.