Centro Nacional de Biotecnología CNB, CSIC, Madrid, Spain.
J Virol. 2021 Jun 24;95(14):e0015021. doi: 10.1128/JVI.00150-21.
is the largest family of plant RNA viruses. Their genomes are expressed through long polyproteins that are usually headed by the leader endopeptidase P1. This protein can be classified as type A or type B based on host proteolytic requirements and RNA silencing suppression (RSS) capacity. The main genus is , and a group of potyviruses infecting sweet potato presents an enlarged P1 protein with a polymerase slippage motif that produces an extra product termed P1N-PISPO. These two proteins display some RSS activity and are expressed followed by HCPro, which appears to be the main RNA silencing suppressor in these viruses. Here, we studied the behavior of the P1 protein of (SPFMV) using a viral system based on a canonical potyvirus, (PPV), and discovered that this protein is able to replace both PPV P1 and HCPro. We also found that P1N-PISPO, produced after polymerase slippage, provides extra RNA silencing suppression capacity to SPFMV P1 in this viral context. In addition, the results showed that presence of two type A P1 proteins was detrimental for viral viability. The ample recombination spectrum that we found in the recovered viruses supports the strong adaptation capacity of P1 proteins and signals the N-terminal part of SPFMV P1 as essential for RSS activity. Further analyses provided data to add extra layers to the evolutionary history of sweet potato-infecting potyvirids. Plant viruses represent a major challenge for agriculture worldwide and , being the largest family of plant RNA viruses, is one of the primary players. P1, the leader endopeptidase, is a multifunctional protein that contributes to the successful spread of these viruses over a wide host range. Understanding how P1 proteins work, their dynamic interplay during viral infection, and their evolutionary path is critical for the development of strategic tools to fight the multiple diseases these viruses cause. We focused our efforts on the P1 protein of , which is coresponsible for the most devastating disease in sweet potato. The significance of our research is in understanding the capacity of this protein to perform several independent functions, using this knowledge to learn more about P1 proteins in general and the potyvirids infecting this host.
是植物 RNA 病毒中最大的家族。它们的基因组通过长多蛋白表达，这些多蛋白通常由头部内切蛋白酶 P1 领导。根据宿主蛋白水解的要求和 RNA 沉默抑制（RSS）能力，这种蛋白可分为 A 型或 B 型。主要属是 ，侵染甘薯的一类 Potyviruses 具有一个扩大的 P1 蛋白，其中包含一个聚合酶滑移基序，产生一个额外的产物，称为 P1N-PISPO。这两种蛋白具有一定的 RSS 活性，并且在 HCPro 之后表达，HCPro 似乎是这些病毒中主要的 RNA 沉默抑制剂。在这里，我们使用基于典型 Potyvirus （PPV）的病毒系统研究了 （SPFMV）的 P1 蛋白的行为，并发现该蛋白能够替代 PPV P1 和 HCPro。我们还发现，聚合酶滑移后产生的 P1N-PISPO 为 SPFMV P1 在这种病毒环境中提供了额外的 RNA 沉默抑制能力。此外，结果表明，存在两种 A 型 P1 蛋白对病毒的生存力有害。我们在回收的病毒中发现的广泛重组谱支持了 P1 蛋白的强大适应性，并表明 SPFMV P1 的 N 端部分对 RSS 活性至关重要。进一步的分析提供了数据，为甘薯侵染 Potyvirids 的进化史增加了额外的层次。植物病毒是全球农业的主要挑战，而 是植物 RNA 病毒中最大的家族，是主要参与者之一。P1，即头部内切蛋白酶，是一种多功能蛋白，有助于这些病毒在广泛的宿主范围内成功传播。了解 P1 蛋白的工作原理、它们在病毒感染过程中的动态相互作用以及它们的进化路径对于开发战略工具来对抗这些病毒引起的多种疾病至关重要。我们将精力集中在 ，这是甘薯中最具破坏性疾病的共同责任人。我们研究的意义在于理解该蛋白执行多个独立功能的能力，利用这些知识了解更多关于 P1 蛋白的一般信息，以及感染该宿主的 Potyvirids。
