ROLE OF HIV-1 GAG MA IN VIRAL ENTRY

描述：HIV-1 Gag基质(Gag MA)，Gag Pr55的N端产物 多聚蛋白，是一种多功能的结构蛋白，参与晚期 病毒生命周期的各个阶段。Gag MA似乎也在病毒中发挥作用 传染性。我们之前已经证明，在病毒感染后， Gag MA与病毒逆转录复合体结合，被磷酸化 并定位于细胞核。我们已经提出了一个模型-牵连GAG MA在 病毒逆转录(RT)复合体的核靶向性，一种功能 这对于HIV-1获得完整的细胞核的能力是重要的 不分裂的细胞，如巨噬细胞。然而，搞笑MA似乎并不是 满足该恶作剧中核蛋白的生化标准 在哺乳动物细胞中表达时定位于细胞质 其他病毒蛋白。此外，一个将Gag MA作为传染性引用的模型 因子通过其肉豆蔻酰化在该Gag MA中创造了一个悖论 部分，针对质膜的GAG前体，病毒的位置 集合。因此，必须以某种方式协调这些相反的目标功能 在病毒生命周期的不同阶段。在上一个资助期，我们 已经获得了实验证据来支持这样一种观点，即Gag MA在 在病毒感染性中的关键作用。GAG MA显示核质穿梭 在病毒生命周期中必不可少的活动。我们的数据表明 在GAG MA中存在核输出信号(NES)，当该信号失活时， 在宿主体内积累Gag前体和基因组病毒RNA的结果 细胞核。我们认为，Gag MA NES抵消了核靶向 病毒产生细胞中的GAG MA以确保病毒粒子的细胞质可利用性 病毒组装过程中的组件。在下一个资助期，我们建议 更全面地表征Gag MA的核质穿梭活性 在病毒生命周期中发挥作用。具体来说，我们建议： 具体目标1：确定GAG MA中管理其 核质穿梭。 具体目标2：确定细胞核进出口因素的特征 介导GAG MA的核质穿梭。 具体目标3：说明GAG MA核出口和 核进口活动在#年的前期和后期得到协调。 病毒生命周期。 具体目标4：检查核质穿梭活动在 病毒在体外和体内的生命周期。 预计这些研究将更充分地定义GAG MA如何 参与病毒生命周期的早期和后期。

DESCRIPTION: HIV-1 gag matrix (gag MA), the N-terminal product of gag Pr55 polyprotein, is a multifunctional structural protein which is involved in late stages of the viral lifecycle. Gag MA also appears to function in viral infectivity. We have previously demonstrated that, following virus infection, gag MA associates with viral reverse transcription complexes, is phosphorylated and localizes to the nucleus. We have proposed a model-implicating gag MA in nuclear targeting of the viral reverse transcription (RT) complex, a function which is important for the ability of HIV-1 to access the intact nucleus of nondividing cells such as macrophages. However, gag MA does not appear to satisfy the biochemical criterion for a nuclear protein in that gag MA localizes to the cytoplasm when expressed in mammalian cells in the absence of other viral proteins. In addition, a model invoking gag MA as an infectivity factor creates a paradox in that gag MA, by virtue of its myristoylation moiety, targets gag precursors to the plasma membrane, the site of virus assembly. Thus, these opposing targeting functions must somehow be coordinated at distinct stages of the virus lifecycle. In the previous funding period, we have obtained experimental evidence to support the notion that gag MA plays a critical role in viral infectivity. Gag MA exhibits nucleocytoplasmic shuttling activity which is essential in the viral lifecycle. Our data suggests the presence of a nuclear export signal (NES) in gag MA which, when inactivated, results in accumulation of gag precursors and of genomic viral RNA in the host cell nucleus. We propose that the gag MA NES counteracts nuclear targeting of gag MA in the virus-producing cell to ensure cytoplasmic availability of virion components during virus assembly. In the next funding period, we propose to more fully characterize how nucleocytoplasmic shuttling activity of gag MA functions in the virus lifecycle. Specifically, we propose to: Specific Aim 1: Identify effector domains in gag MA that govern its nucleocytoplasmic shuttling. Specific Aim 2: Characterize cellular nuclear import and export factors that mediate nucleocytoplasmic shuttling of gag MA. Specific Aim 3: Characterize the mechanism by which gag MA nuclear export and nuclear import activity is coordinated during early and late phases of the virus lifecycle. Specific Aim 4: Examine the role of nucleocytoplasmic shuttling activity in the virus lifecycle both in vitro and in vivo. It is expected that these studies will more fully define how gag MA participates in early and late phases of the viral lifecycle.