Levy Amit, Tilsner Jens
Department of Plant Pathology, University of Florida, Gainesville, FL, United States.
Citrus Research and Education Center, University of Florida, Lake Alfred, FL, United States.
Front Plant Sci. 2020 Jul 3;11:862. doi: 10.3389/fpls.2020.00862. eCollection 2020.
To infect their hosts and cause disease, plant viruses must replicate within cells and move throughout the plant both locally and systemically. RNA virus replication occurs on the surface of various cellular membranes, whose shape and composition become extensively modified in the process. Membrane contact sites (MCS) can mediate non-vesicular lipid-shuttling between different membranes and viruses co-opt components of these structures to make their membrane environment suitable for replication. Whereas animal viruses exit and enter cells when moving throughout their host, the rigid wall of plant cells obstructs this pathway and plant viruses therefore move between cells symplastically through plasmodesmata (PD). PD are membranous channels connecting nearly all plant cells and are now viewed to constitute a specialized type of endoplasmic reticulum (ER)-plasma membrane (PM) MCS themselves. Thus, both replication and movement of plant viruses rely on MCS. However, recent work also suggests that for some viruses, replication and movement are closely coupled at ER-PM MCS at the entrances of PD. Movement-coupled replication at PD may be distinct from the main bulk of replication and virus accumulation, which produces progeny virions for plant-to-plant transmission. Thus, MCS play a central role in plant virus infections, and may provide a link between two essential steps in the viral life cycle, replication and movement. Here, we provide an overview of plant virus-MCS interactions identified to date, and place these in the context of the connection between viral replication and cell-to-cell movement.
为了感染宿主并引发疾病,植物病毒必须在细胞内进行复制,并在植物体内进行局部和系统性传播。RNA病毒的复制发生在各种细胞膜表面,在此过程中,细胞膜的形状和组成会发生广泛改变。膜接触位点(MCS)可以介导不同膜之间的非囊泡脂质穿梭,病毒会利用这些结构的成分来使其膜环境适合复制。动物病毒在其宿主内移动时进出细胞,而植物细胞的刚性细胞壁阻碍了这一途径,因此植物病毒通过胞间连丝(PD)在细胞间进行共质体移动。PD是连接几乎所有植物细胞的膜性通道,现在被认为本身就构成了一种特殊类型的内质网(ER)-质膜(PM)MCS。因此,植物病毒的复制和移动都依赖于MCS。然而,最近的研究还表明,对于一些病毒来说,复制和移动在PD入口处的ER-PM MCS处紧密耦合。PD处与移动相关的复制可能与主要的复制和病毒积累不同,后者产生用于植物间传播的子代病毒粒子。因此,MCS在植物病毒感染中起着核心作用,并且可能在病毒生命周期的两个关键步骤——复制和移动之间提供联系。在这里,我们概述了迄今为止已确定的植物病毒与MCS的相互作用,并将其置于病毒复制与细胞间移动之间联系的背景下进行讨论。