Roles of Gag and NCp7 in Facilitating tRNA3Lys Annealing to Viral RNA in Human Immunodeficiency Virus Type 1
Roles of Gag and NCp7 in Facilitating tRNA3Lys Annealing to Viral RNA in Human Immunodeficiency Virus Type 1
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DOI：
10.1128/jvi.00488-09
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发表时间：
2009-08-15
影响因子：
5.4
通讯作者：
Kleiman, Lawrence
中科院分区：
文献类型：
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作者：
Guo, Fei;Saadatmand, Jenan;Kleiman, Lawrence
在蛋白酶阴性人类免疫缺陷病毒 1 型 (HIV-1) [Pr(-)] 中，与蛋白酶阳性 HIV-1 [Pr(+)] 中成熟核衣壳 (NCp7) 退火的 tRNA(3)(Lys) 量相比，Gag 退火的 tRNA(3)(Lys) 量略有减少（大约 25%）。然而，Gag 退火后的 tRNA(3)(Lys) 启动逆转录的能力也大大降低，并且与病毒 RNA 的结合也较不紧密。在体内和体外，APOBEC3G (A3G) 抑制 NCp7 促进的 tRNA(3)(Lys) 退火，但不抑制 Gag 促进的退火。虽然在体外将 Pr(-) 病毒 RNA 短暂暴露于 NCp7 会使 tRNA(3)(Lys) 退火的质量和数量恢复到 Pr(+) 水平，但 A3G 的存在既阻止了这种救援，又进一步减少了 tRNA(3)(Lys) 退火。由于 A3G 在体外抑制 NCp7 促进的 tRNA(3)(Lys) 退火需要在退火过程中存在 A3G，因此这些结果表明，在 Pr(+) 病毒中 NCp7 可以取代 Gag 退火的 tRNA(3)(Lys) 并将其重新退火为病毒 RNA，重新退火步骤受到 A3G 抑制。这支持了野生型 Pr(+) 病毒中 tRNA(3)(Lys) 的初始退火可能是由 Gag 而不是 NCp7 进行的可能性，这可能提供了 Gag 偏好与 tRNA(3)(Lys) 退火区域附近的病毒 RNA 5' 区域中的 RNA 茎环结合的优势。
In protease-negative human immunodeficiency virus type 1 (HIV-1) [Pr(-)], the amount of tRNA(3)(Lys) annealed by Gag is modestly reduced (similar to 25%) compared to that annealed by mature nucleocapsid (NCp7) in protease-positive HIV-1 [Pr(+)]. However, the tRNA(3)(Lys) annealed by Gag also has a strongly reduced ability to initiate reverse transcription and binds less tightly to viral RNA. Both in vivo and in vitro, APOBEC3G (A3G) inhibits tRNA(3)(Lys) annealing facilitated by NCp7 but not annealing facilitated by Gag. While transient exposure of Pr(-) viral RNA to NCp7 in vitro returns the quality and quantity of tRNA(3)(Lys) annealing to Pr(+) levels, the presence of A3G both prevents this rescue and creates a further reduction in tRNA(3)(Lys) annealing. Since A3G inhibition of NCp7-facilitated tRNA(3)(Lys) annealing in vitro requires the presence of A3G during the annealing process, these results suggest that in Pr(+) viruses NCp7 can displace Gag-annealed tRNA(3)(Lys) and re-anneal it to viral RNA, the re-annealing step being subject to A3G inhibition. This supports the possibility that the initial annealing of tRNA(3)(Lys) in wild-type, Pr(+) virus may be by Gag and not by NCp7, perhaps offering the advantage of Gag's preference for binding to RNA stem-loops in the 5' region of viral RNA near the tRNA(3)(Lys) annealing region.