ROLE OF HIV-1 GAG MA IN VIRAL ENTRY

描述：HIV-1 gag基质（gag MA），gag Pr 55的N-末端产物 多聚蛋白，是一种多功能结构蛋白，参与晚期 病毒生命周期的各个阶段。Gag MA似乎也在病毒感染中起作用。 传染性我们以前已经证明，在病毒感染后， gag MA与病毒逆转录复合物结合，被磷酸化 并定位于细胞核。我们提出了一个模型，涉及gag MA在 病毒逆转录（RT）复合物的核靶向， 这对HIV-1进入完整的细胞核的能力很重要， 非分裂细胞如巨噬细胞。然而，gag MA似乎并不 满足该gag MA中核蛋白的生化标准 当在哺乳动物细胞中表达时， 其他病毒蛋白此外，一个模型调用gag MA作为传染性 由于豆蔻酰化， 部分，靶向gag前体到质膜，病毒的网站 组装件.因此，必须以某种方式协调这些对立的目标功能 在病毒生命周期的不同阶段在上一个融资周期，我们 已经获得了实验证据来支持这一观点，即gag MA发挥了 在病毒感染性中起着关键作用。Gag MA显示核质穿梭 在病毒生命周期中至关重要的活性。我们的数据显示 在gag MA中存在核输出信号（内斯），当其失活时， 导致gag前体和基因组病毒RNA在宿主中积累 细胞核我们认为，gag MA内斯抵消了核靶向 在病毒产生细胞中使用gag MA，以确保病毒粒子的细胞质可用性 病毒组装过程中的组件。在下一个拨款期内，我们建议 更充分地表征gag MA的核质穿梭活性如何 在病毒生命周期中发挥作用。具体而言，我们建议： 具体目的1：鉴定gag MA中调控其表达的效应子结构域。 核质穿梭 具体目标2：表征细胞核输入和输出因子， 介导gag MA的核质穿梭。 具体目标3：表征gag MA核输出和 核进口活动在项目的早期和后期阶段得到协调， 病毒生命周期 具体目标4：检查核质穿梭活性在细胞凋亡中的作用。 病毒的生命周期在体外和体内。 预计这些研究将更全面地定义gag MA 参与病毒生命周期的早期和晚期阶段。

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.