The biosynthesis of membrane-bound M13 coat protein. Energetics and assembly intermediates.
The biosynthesis of membrane-bound M13 coat protein. Energetics and assembly intermediates.
复制标题
膜结合 M13 外壳蛋白的生物合成。
DOI：
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发表时间：
1982
影响因子：
4.8
通讯作者：
W. Wickner
中科院分区：
文献类型：
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作者：
R. Zimmermann;C. Watts;W. Wickner
噬菌体M13的主要外壳蛋白在组装成挤压病毒之前跨越被感染细胞的质膜。它最初是一个前体，称为原衣，在其NH2末端有23个残基先导序列。原衣被发现与质膜的内表面结合。细胞膜的电位是原衣插入和转化为被衣蛋白所必需的，尽管这些事件的顺序尚不清楚。我们现在报告了从病毒M13am8H1R6突变原衣（procoat-R6）到突变外壳（coat R6）的转化研究。原毛- r6的行为与野生型原毛在三个方面不同。(i)脉冲标记的原蛋白- r6大量插入细胞膜。这表明前导肽酶的活性位点位于质周膜表面，并且在野生型原衣加工之前插入。（ii）尽管在m13am8h1r6感染的细胞中插入的原衣- r6比在野生型感染中插入的原衣更丰富，但原衣- r6被加工成外套- r6的速度比原衣转化为外套的速度慢。（iii）原涂层- r6的膜插入和蛋白水解过程对解偶联剂几乎完全不敏感。我们提出了一个外壳蛋白生物合成的能量学和组装中间体的工作模型。
The major coat protein of bacteriophage M13 spans the plasma membrane of infected cells prior to its assembly into extruding virus. It is initially made as a precursor, termed procoat, with a 23-residue leader sequence at its NH2 terminus. Procoat is found bound to the inner surface of the plasma membrane. The electrical potential of the cell membrane is required for procoat insertion and conversion to coat protein, although the order of these events has been unknown. We now report studies of the conversion of a mutant procoat (procoat-R6) from the virus M13am8H1R6 to mutant coat (coat R6). The behavior of procoat-R6 differs from that of the wild type procoat in three respects. (i) Pulse-labeled procoat-R6 is largely found inserted across the cell membrane. This suggests that the active site of leader peptidase is on the periplasmic membrane face and that insertion normally precedes processing for wild type procoat as well. (ii) Despite the greater abundance of inserted procoat-R6 in M13am8H1R6-infected cells than inserted procoat in wild type infections, procoat-R6 is processed to coat-R6 more slowly than procoat is converted to coat. (iii) The membrane insertion and proteolytic processing of procoat-R6 are almost completely insensitive to uncouplers. We present a working model for the energetics and assembly intermediates of coat protein biosynthesis.