HIV-1 Gag Precursor Protein Interactions

尽管在艾滋病诊断和治疗方面取得了很大进展，但艾滋病的持续流行需要 继续努力了解艾滋病毒复制的各个方面，并开发新的抑制方法。 在追求这些目标的过程中，我们试图定义HIV-1结构域的活动和相互作用， (Gag)蛋白质，特别关注N-末端基质（MA）结构域。Gag蛋白最初是 合成为前体Gag（PrGag）蛋白，其在MA的N-末端被肉豆蔻酰化，并且MA 结构域靶向PrGag递送至质膜（PM）病毒组装位点， 信号磷脂磷脂酰肌醇-4，5-二磷酸（PI[4，5]P2）。证据还表明， MA-RNA结合有助于蛋白伴侣PrGag蛋白组装位点，并且病毒膜是 富含脂筏成分如胆固醇、鞘磷脂和神经酰胺。除了其 由于MA的贩运作用，已显示MA影响野生型（WT）HIV-1包膜（Env）的掺入 糖蛋白三聚体转化为病毒颗粒。以前的研究表明，HIV-1 Env蛋白， 在它们的跨膜（TM; gp 41）结构域中携带胞质尾缺失（CDCT）的细胞可以被掺入到 病毒体的方式是细胞类型依赖性的，但MA独立。相比之下， 已鉴定WT Env掺入病毒体中。此外，其他MA突变已被证明， 抑制由MA突变或Env CT突变引起的Env掺入缺陷。等 观察表明可能存在直接的MA-CT相互作用，但缺乏证据。期间 在过去的资助期间，我们在理解MA和Env蛋白如何相互作用方面取得了重大进展。 我们已经表明MA直接结合Env CT，并且该结合依赖于MA三聚化。我们有 证明HIV-1 Env CT的C-末端两亲螺旋参与MA结合， MA-CT结合被MA-RNA结合阻断。我们已经发现脂质成分的变化， WT Env活性，并获得了CT加工的新证据。以此为基础，我们 提出了MA-CT相互作用的特征和这些相互作用在HIV-1复制中的作用。 特别是，我们将定义Env蛋白如何与MA三聚体和晶格结合，以确定如何 WT Env蛋白被整合到病毒颗粒中;我们将研究Gag和Env蛋白是如何被整合到病毒颗粒中的。 在病毒颗粒中合作以执行它们的功能。我们的研究结果将有助于阐明艾滋病毒Gag和Env 蛋白质的合作，并将促进新的方法来干扰HIV-1复制的发展。

Despite great advances in AIDS diagnosis and treatment, the continuing AIDS epidemic demands continuing efforts to understand all aspects of HIV replication and to develop new methods for its inhibition. In pursuit of these goals, we have sought to define the activities and interactions of the HIV-1 structural (Gag) proteins, with a specific focus on the N-terminal matrix (MA) domain. The Gag proteins initially are synthesized as precursor Gag (PrGag) proteins that are myristoylated at the N-terminus of MA, and MA domains target PrGag delivery to plasma membrane (PM) virus assembly sites virtue of preferential binding to the signaling phospholipid phosphatidylinositol-4,5-bisphosphate (PI[4,5]P2). Evidence also indicates that MA-RNA binding helps chaperone PrGag proteins to assembly sites, and that virus membranes are enriched for lipid raft constituents such as cholesterol, sphingomyelin, and ceramide. In addition to its trafficking role, MA has been shown to influence the incorporation of wild type (WT) HIV-1 envelope (Env) glycoprotein trimers into virus particles. Previous investigations have shown that HIV-1 Env proteins that carry cytoplasmic tail deletions (CT) in their transmembrane (TM; gp41) domains can be incorporated into virions in a fashion that is cell type-dependent, but MA-independent. In contrast, MA mutations that impair WT Env incorporation into virions have been identified. Moreover, other MA mutations have been shown to suppress Env incorporation defects imposed either by MA mutations, or Env CT mutations. Such observations imply that there could be direct MA-CT interactions, but proof has been lacking. During the past funding period, we have made significant progress in understanding how MA and Env proteins interact. We have shown that MA directly binds to Env CTs, and that binding depends on MA trimerization. We have demonstrated that C-terminal amphipathic helices of HIV-1 Env CTs are involved in MA binding, and that MA-CT binding is blocked by MA-RNA binding. We have discovered lipid composition changes that perturb WT Env activity, and have obtained novel evidence of CT processing. Using this as a foundation, we propose the characterization of MA-CT interactions and the roles of these interactions in HIV-1 replication. In particular, we will define how Env proteins associate with MA trimers and lattices so as to determine how WT Env proteins become incorporated into virus particles; and we will examine how Gag and Env proteins collaborate in virus particles to perform their functions. Our results will help clarify how HIV Gag and Env proteins cooperate, and will foster the development of novel approaches to interfere with HIV-1 replication.