Unravelling the nuclear manipulation by geminiviruses

双病毒是具有环状基因组的单链（ss） DNA植物病毒的一大群，具有重要的经济意义，是世界范围内毁灭性作物疾病的致病因子。双病毒复制发生在细胞核内，利用植物DNA复制机制；双病毒基因组形成小染色体并受到表观遗传修饰，这似乎在双病毒与植物相互作用的结果中起重要作用；病毒囊化也发生在细胞核中。很明显，细胞核是双病毒入侵的最重要的亚细胞区室；然而，缺乏有关病毒相关过程亚核分布的空间信息。有趣的是，双病毒感染和/或特定病毒蛋白的表达会引起核结构的特征性变化，例如，当Abutilon花叶病毒转运蛋白MP和NSP联合表达时，核膜衍生的囊泡内陷到核内，但也出现与核表面相关。此外，双病毒感染细胞中核标记物定位的变化也反映了核组织的改变。这些观察结果表明，植物病毒复制和穿梭/运动蛋白的协同作用导致核和膜结构域的重组，这可能是病毒复制、逃避植物抗病毒机制和运输的必要条件。因此，本提案的目标是：(1)深入了解双子座病毒的核重组和操纵；Ii)确定双病毒的核相互作用；iii)确定病毒操纵的核目标。核进口、颠覆、出口都是建立病毒感染必不可少的；深入了解这些过程是如何发生的，将为设计有效的抗病毒策略铺平道路。因为旨在削弱病毒对细胞核的共同选择的策略可能会影响病毒的复制，它们将最大限度地减少潜在突变病毒版本的出现，从而提供持久的抵抗力。

Geminiviruses constitute a large and economically important group of single-stranded (ss) DNA plant viruses with circular genomes, causal agents of devastating crop diseases worldwide. Geminiviral replication occurs in the nucleus and uses the plant DNA replication machinery; the geminiviral genome forms minichromosomes and is subjected to epigenetic modifications, which seem to play an important role in the outcome of geminivirus-plant interactions; viral encapsidation also takes place in the nucleus. It is obvious that the nucleus is the most important subcellular compartment for geminiviral invasion; spatial information regarding the subnuclear distribution of virus-related processes, however, is lacking. Interestingly, geminiviral infection and/or expression of specific viral proteins induce characteristic changes in nuclear architecture, e.g. upon combined expression of Abutilon mosaic virus transport proteins, MP and NSP, inner nuclear envelope-derived vesicles invaginate into nuclei, but also appear associated with the nuclear surface. Additionally, changes in the localization of nuclear markers in geminivirus-infected cells also reflect an alteration of nuclear organization. These observations suggest that a concerted action of plant viral replication and shuttling/movement proteins leads to the re-organization of nuclear and membrane domains, which might be essential for viral replication, evasion of plant anti-viral mechanisms, and trafficking. Thus, the objectives of this proposal are i) to gain insight into the nuclear reorganization and manipulation by geminiviruses; ii) to define the nuclear interactome of geminiviruses; and iii) to identify nuclear targets of viral manipulation. Nuclear import, subversion, and export are essential for the establishment of the viral infection; a deep understanding of how these processes occur would pave the way for the design of efficient anti-viral strategies. Because strategies aimed at impairing the viral co-option of the nucleus would potentially impact viral replication, they would minimize the appearance of potential mutated viral versions, hence providing durable resistance.