HIV Release and Restriction

摘要 本项目旨在阐明HIV-1萌发及其被宿主抑制的机制基础 逆转录因子CHMP3。为了启动萌发，HIV-1 Gag与ESCRT-I1-4和ALIX5-7结合，这两个早期作用因子在 运输所需的宿主内体分选复合体(ESCRT)途径。这些因素反过来又招募了 迟效ESCRT因子CHMP2、CHMP4(ESCRT-III)和Vps4(AAA-ATPase)2、8-10(参考文献)。 11-16)。已经提出了许多膜收缩和分裂的模型。17-26我们倾向于那些 其中：1)ESCRT-III蛋白形成螺旋状的细丝，招募Vps4并收缩膜颈部 2)Vps4 ATPase通过重塑潜在的ESCRT-III促进脂质混合 脚手架。我们现在建议确定ESCRT-III细丝重塑膜的结构基础。 和Vps4(目标1和2)，描述了哺乳动物反转录CHMP3(ESCRT-III)蛋白如何抑制HIV 萌芽而不诱导细胞毒性(目标3)，并通过以下方法成像萌芽病毒粒子内的ESCRT组件 电子冷冻断层摄影术(目标4)。这些研究将揭示HIV-1如何利用宿主ESCRT-III/Vps4 退出细胞的机制，以及宿主反转录CHMP3蛋白如何特异性地抑制这一过程。

ABSTRACT This Project is designed to elucidate the mechanistic bases for HIV-1 budding and its inhibition by the host factor retroCHMP3. To initiate budding, HIV-1 Gag binds ESCRT-I1-4 and ALIX5-7, two early-acting factors in the host Endosomal Sorting Complexes Required for Transport (ESCRT) pathway. These factors, in turn, recruit the late-acting ESCRT factors CHMP2, CHMP4 (ESCRT-III) and VPS4 (AAA ATPase)2,8-10 (reviewed in refs. 11-16). Numerous models for membrane constriction and fission have been proposed.17-26 We favor those in which: 1) ESCRT-III proteins form spiraling filaments that recruit VPS4 and constrict the membrane neck from the cytoplasmic face and 2) The VPS4 ATPase promotes lipid mixing by remodeling the underlying ESCRT-III scaffold. We now propose to determine the structural bases for membrane remodeling by ESCRT-III filaments and VPS4 (Aims 1 and 2), characterize how mammalian retroCHMP3 (ESCRT-III) proteins can inhibit HIV budding without inducing cellular toxicity (Aim 3), and image ESCRT assemblies within budding virions by electron cryotomography (Aim 4). These studies will reveal how HIV-1 uses the host ESCRT-III/VPS4 machinery to exit cells and how host retroCHMP3 proteins can specifically inhibit this process.