Sagher D, Harvey R G, Hsu W T, Weiss S B
Proc Natl Acad Sci U S A. 1979 Feb;76(2):620-4. doi: 10.1073/pnas.76.2.620.
Previous studies have shown that alkylation of MS2 RNA by certain derivatives of polycyclic aromatic hydrocarbons renders it noninfectious. Since phage RNA serves as a template for translation and transcription, either of these RNA-directed processes, or both, could be responsible in vivo for the inhibition of phage replication by metabolically activated hydrocarbons. The present study correlates the degree of inhibition of MS2 RNA infectivity, at various levels of alkylation by (+/-)-trans, 7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydrobenzol[a]pyrene, with the translation efficiency in vitro of the same alkylated RNA for the synthesis of viral synthetase and of maturation and coat proteins. The results indicate that dihydroxyepoxy-tetrahydrobenzo[a]pyrene modification of MS2 RNA impairs its template capacity for the synthesis of phage-specific proteins; this inhibition is insufficient, however, to account for the loss of RNA infectivity at lower molar ratios of alkylation. For the three viral proteins synthesized in vitro, the translation of RNA synthetase is much more sensitive to MS2 RNA modification than either coat or maturation protein synthesis. Our results also indicate that the loss of viral RNA infectivity follows a single-hit inactivation mechanism, whereas several alkylation events in the viral RNA synthetase cistron may be necessary to block translation of this gene product.
先前的研究表明，多环芳烃的某些衍生物对MS2 RNA进行烷基化会使其失去感染性。由于噬菌体RNA作为翻译和转录的模板，这些RNA导向的过程中的任何一个，或两者都可能在体内导致代谢活化的碳氢化合物抑制噬菌体复制。本研究将（±）-反式-7,8-二羟基-反式-9,10-环氧-7,8,9,10-四氢苯并[a]芘在不同烷基化水平下对MS2 RNA感染性的抑制程度，与相同烷基化RNA体外合成病毒合成酶、成熟蛋白和外壳蛋白的翻译效率相关联。结果表明，二羟基环氧四氢苯并[a]芘对MS2 RNA的修饰损害了其合成噬菌体特异性蛋白的模板能力；然而，这种抑制不足以解释在较低烷基化摩尔比下RNA感染性的丧失。对于体外合成的三种病毒蛋白，RNA合成酶的翻译比外壳蛋白或成熟蛋白合成对MS2 RNA修饰更为敏感。我们的结果还表明，病毒RNA感染性的丧失遵循单打击失活机制，而病毒RNA合成酶顺反子中的几个烷基化事件可能是阻断该基因产物翻译所必需的。
