Translation Regulation by Enterovirus Proteinase

描述（由申请人提供）：本研究的长期目标是 了解肠道病毒如脊髓灰质炎病毒（PV）和 柯萨奇病毒（CVB 3）几乎抑制所有细胞mRNA的翻译， 刺激病毒RNA在受感染的HeLa细胞中的有效翻译， 称为主机转换关闭。先前的研究表明PV和CVB 3 感染导致翻译起始因子eIF 4G的切割 由病毒2A蛋白酶和其他细胞蛋白酶介导的反应。这 用于重新启动帽依赖性翻译起始， 帽依赖性翻译起始机制的现有模型不能 解释了病毒感染中细胞mRNA的持续翻译 含有胍或甲基-槲皮素，其中eIF 4G被完全裂解。 这种翻译可能是由核糖体通过5 '-3'端的重新起始介导的。 mRNA的相互作用。因此，eIF 4G裂解加上额外的事件必须 完全阻断宿主翻译的位置;我们假设病毒 蛋白酶介导的多聚腺苷酸结合蛋白（PABP）的裂解可以同样 重要.我们最近发现病毒3C蛋白酶可以有效地 在PABP被部分切割的反应中阻断翻译，而eIF 4GI和 eIF 4GII保持完整，从而为生物学提供了直接证据。 PABP裂解的相关性。被病毒蛋白酶切割的PABP区域是 对它的了解很少，但可能在60 S核糖体连接步骤中起作用， 并可能调节同一转录本上核糖体的重新起始 以5 ′-3 ′相互作用依赖的机制。我们发现PABP的裂解是由 病毒蛋白酶关注翻译调控的新领域 涉及5 '-3'相互作用，这是当前非常感兴趣的领域。目标在 该建议将（1）确定哪些PABP库被切割，（2）确定 PABP裂解对其各种功能的影响，特别是 可能支持核糖体再起始的PABP（3）决定了相对作用 PABP和eIF 4G切割在体内翻译控制中的作用，以及（4）还将 确定PABP裂解是否在从病毒翻译到 病毒RNA复制

DESCRIPTION (provided by applicant): The long term goal of this research is to understand the mechanism by which enteroviruses such as poliovirus (PV) and Coxsackievirus (CVB3) inactivate translation of nearly all cellular mRNA while stimulating efficient translation of virus RNA in infected HeLa cells, an event known as host translation shutoff. Previous work has shown that PV and CVB3 infection result in cleavage of the translation initiation factor eIF4G in reactions mediated by the virus 2Aprotease and other cellular proteases. This serves to inactivate de novo cap-dependent translation initiation however, existing models for cap-dependent translation initiation mechanism cannot account for continued translation of cellular mRNA in virus infections containing guanidine or methyl-quercitin in which eIF4G is totally cleaved. This translation is likely mediated by ribosome re-initiation via 5'-3' interactions on mRNA. Thus eIF4G cleavage plus additional events must take place to completely block host translation; we hypothesize that viral protease-mediated cleavage of poly(A)-binding protein (PABP) may be equally important. We have recently discovered that viral 3Cprotease can effectively block translation in reactions in which PABP is partly cleaved, yet eIF4GI and eIF4GII remain intact, thus providing direct evidence for the biological relevance of PABP cleavage. The region of PABP cleaved by viral protease is poorly understood but may function in the 60S ribosome joining step of translation and may regulate re-initiation of ribosomes on the same transcript in a 5'-3' interaction-dependent mechanism. Our discovery of PABP cleavage by viral proteases focuses attention on new areas of translation regulation involving 5'-3' interactions, an area of intense current interest. The aims in this proposal will (1) determine which pools of PABP are cleaved, (2) determine the impact of PABP cleavage on its various functions, particularly functions of PABP which may support ribosome re-initiation (3) determine the relative roles of PABP and eIF4G cleavage in translation control in vivo and (4) will also determine if PABP cleavage plays a role in the switch from viral translation to viral RNA replication.