Effect of APOBEC3G on retroviruses and retrotransposons

APOBEC3G 对逆转录病毒和逆转录转座子的影响

• 批准号: 6947390
• 负责人: BRYAN R. CULLEN
• 金额: $ 36.45万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-02-15 至 2010-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6947390
• 关键词: Retroviridae; aminohydrolases; antiviral agents; biochemical evolution; fungal proteins; genetic screening; species difference; transposon /insertion element; virion; virus replication

Much is now known about not only the inhibitory effect of APOBEC3G, and other related APOBEC3 proteins, on HIV-1 replication but also the mechanism of APOBEC3G neutralization by HIV-1 Vif. However, the APOBEC3 protein family must be evolutionarily conserved in humans for reasons unrelated to HIV-1 infection, as this virus only entered the human population relatively recently. In this grant, we focus on understanding the role and mechanism of action of APOBEC3G, and related proteins, in controlling not only retroviruses distinct from HIV-1, but also LTR retrotransposons, a key class of endogenous genomic parasites. In the case of primate foamy virus (PFV), the prototype of a ubiquitous family of non-pathogenic retroviruses, we present evidence for a novel functional homolog of Vif, termed Bet that specifically binds to APOBEC3G in vivo. In the absence of a functional Bet protein, PFV is highly susceptible to APOBEC3G, which packages into PFV virions and induces editing of nascent proviruses. How APOBEC3G packages into PFV virions is unclear, as PFV Gag does not contain sequences related to the HIV-1 nucleocapsid zinc fingers implicated in virion packaging of APOBEC3G. In the case of murine leukemia virus (MLV), a prototypic oncoretrovirus, human APOBEC3G is highly inhibitory while murine APOBEC3 is far less so and is excluded from MLV virions. We will seek to identify the determinants regulating MLV virion incorporation of these proteins and their ability to bind MLV Gag. Finally, we have obtained exciting new data showing that human APOBEC3G can specifically block retrotransposition of Tyl in yeast cells. We will seek to identify the mechanism underlying this inhibition and, most importantly, will attempt to use genetic approaches to identify yeast proteins that facilitate inhibition of Tyl retrotransposition by APOBEC3G as a way of potentially identifying analogous APOBEC3G co-factors in HIV-1 infected human cells. Together, these data should shed significant light on the role and mechanism of action of APOBEC3G and related proteins and pave the way for future research aimed at enhancing or protecting APOBEC3G function and thereby inhibiting HIV-1 replication in vivo.

目前，我们不仅对APOBEC3G和其他相关的APOBEC3蛋白对HIV-1复制的抑制作用了解甚多，而且对APOBEC3G被HIV-1 Vif中和的机制也了解甚多。然而，由于与HIV-1感染无关的原因，APOBEC3蛋白家族在人类中必须是进化保守的，因为这种病毒是最近才进入人类群体的。在这项资助中，我们专注于了解APOBEC3G及其相关蛋白在控制与HIV-1不同的逆转录病毒以及LTR逆转录转座子（内源性基因组寄生虫的关键类别）中的作用和作用机制。灵长类泡沫病毒（PFV）是一种普遍存在的非致病性逆转录病毒家族的原型，我们提供了Vif的一种新的功能同源物的证据，称为Bet，它在体内特异性地结合APOBEC3G。在缺乏功能性的Bet蛋白的情况下，PFV对APOBEC3G非常敏感，APOBEC3G可以打包到PFV病毒粒子中并诱导新生前病毒的编辑。APOBEC3G如何包装成PFV病毒粒子尚不清楚，因为PFV Gag不包含与APOBEC3G病毒粒子包装中涉及的HIV-1核衣壳锌指相关的序列。在小鼠白血病病毒（MLV）中，人类的APOBEC3G具有高度的抑制作用，而小鼠的APOBEC3则远低于此，并且被排除在MLV病毒粒子之外。我们将寻求确定调节MLV病毒粒子结合这些蛋白质及其结合MLV Gag的能力的决定因素。最后，我们获得了令人兴奋的新数据，表明人类APOBEC3G可以特异性阻断酵母细胞中Tyl的反转录转位。我们将试图确定这种抑制的机制，最重要的是，我们将尝试使用遗传方法来鉴定酵母蛋白，这些酵母蛋白促进了APOBEC3G对Tyl逆转录转位的抑制，作为鉴定HIV-1感染的人类细胞中类似APOBEC3G辅助因子的一种潜在方法。总之，这些数据应该对APOBEC3G和相关蛋白的作用和作用机制有重要的揭示，并为未来旨在增强或保护APOBEC3G功能从而抑制HIV-1在体内复制的研究铺平道路。