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首页> 外文期刊>Journal of Virology >Synthesis and processing of polymerase proteins of wild-type and mutant avian retroviruses.
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Synthesis and processing of polymerase proteins of wild-type and mutant avian retroviruses.

机译：野生型和突变体逆转录病毒聚合酶蛋白的合成与加工。

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We have studied the biosynthesis of avian retrovirus proteins related to reverse transcriptase in permissive avian embryonic cells. Analysis of immune precipitates from avian sarcoma virus (ASV)-infected cells demonstrated the presence of the 180,000-dalton gag-pol "read-through" protein (Pr180gag-pol) and a 130,000-dalton polypeptide (Pr130gag-pol). Pr130gag-pol was found, in serological and peptide mapping studies, to consist primarily of sequences related to reverse transcriptase and the gag-encoded protein p15. Pr180gag-pol was found to be phosphorylated, whereas Pr130gag-pol was not. In addition, only Pr180gag-pol but not Pr130gag-pol was susceptible to cleavage with the virion protease p15. Although the structure of Pr130gag-pol would suggest that it is generated by removal of a portion of the gag region from Pr180gag-pol, an analysis of labeling kinetics has failed to demonstrate unequivocally whether Pr130gag-pol is a cleavage product of Pr180gag-pol or a primary translation product. We were repeatedly unable to detect either Pr180gag-pol or Pr130gag-pol in virus particles released from the cell, whereas both beta and alpha subunits were readily observed. Several presumed intermediates between Pr130gag-pol and the beta subunit of reverse transcriptase were also observed in virions. These studies indicate cleavage of polyemrase precursors at the time of virus budding. On the basis of these data, we present a processing scheme for the generation of reverse transcriptase subunits. We have also examined reverse transcriptase biosynthesis in cells producing two mutants that fail to package the enzyme. Previous work showed that integrated proviruses of both mutants are missing DNA sequences in pol: one mutant, PH9 (Mason et al., J. Virol. 30:132-140, 1979), contains a deletion near the 3' end of pol, whereas the other, SE52d (linial et al., Virology 87:130-141, 1978), may have inserted a host cell sequence near the 5' end of pol. Neither mutant synthesized Pr180gag-pol or Pr130gag-pol, but instead produced novel proteins comprised of sequences shared with gag proteins plus a region antigenically related to reverse transcriptase. Both proteins were defective as precursors to reverse transcriptase. Whereas Pr180gag-pol and Pr130gag-pol were precipitated by an antiserum raised against p32 (a virion protein derived from the portion of the beta subunit removed during processing of beta to alpha [Schiff and Grandgenett, J. Virol. 28:279-291, 1978]), the novel protein synthesized by PH9 ws not precipitated. This suggets that the alpha subunit is generated by a COOH-terminal cleavage of the beta subunit.
机译：我们研究了禽胚胎细胞中逆转录酶相关的禽逆转录病毒蛋白的生物合成。来自禽Sarcoma病毒（ASV）的免疫沉淀物分析 - 培养的细胞显示出180,000-Dalton Gag-Pol“读数”蛋白（PR180GAG-POL）和130,000-Dalton多肽（PR130GAG-POL）的存在。在血清学和肽映射研究中发现了PR130GAG-POL，主要由与逆转录酶和GAG编码蛋白P15相关的序列组成。 PR180GAG-POL被发现磷酸化，而PR130GAG-POL不是。此外，仅PR180GAG-POL但不是PR130GAG-POL易于用病毒素蛋白酶P15切解。尽管PR130GAG-POL的结构建议，通过从PR180GAG-POL去除一部分GAG区域产生的，标记动力学的分析未能证明PR130GAG-POL是否是PR180GAG-POL的切割产物或主要翻译产品。我们反复检测从细胞释放的病毒颗粒中检测PR180GAG-POL或PR130GAG-POL，而易于观察到β和α亚基。在病毒粒中也观察到PR130GAG-POL和逆转录酶的β亚基之间的几种预示中间体。这些研究表明在病毒萌芽时的聚溶酶前体的切割。在这些数据的基础上，我们提出了一种用于产生逆转录酶亚基的处理方案。我们还检查了产生两个未包装酶的突变体的细胞中的逆转录酶生物合成。以前的工作表明，两种突变体的综合潜水缺失在Pol：一个突变体pH9（Mason等，J.Virol.30：132-140,1979）中缺少DNA序列（Mason等，J.Virol。），含有靠近Pol的3'末端附近的删除，而另一个，SE52D（Linial等，病毒学87：130-141,1978）可以在Pol的5'末端附近插入宿主细胞序列。突变均合成PR180GAG-POL或PR130GAG-POL，而是制备由与GAG蛋白共享的序列组成的新型蛋白质加上抗原与逆转录酶有关的区域。两种蛋白质都像逆转录酶一样有缺陷。虽然PR180GAG-POL和PR130GAG-POL通过针对P32升高的抗血清（衍生自β亚基部分的病毒蛋白蛋白在β至α-α-α-α[vallgenett，J.ivol。28：279-291）中衍生自β亚基部分。28：279-291， 1978]），通过PH9 Ws合成的新蛋白质未沉淀。通过β亚基的COOH-末端切割产生α亚基的这种酶。

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