Turnip mosaic virus (TuMV), belonging to the genus Potyvirus (family Potyviridae), has a large host range and consists of a single-stranded positive sense RNA genome encoding 12 proteins, including the P1 protease. This protein which is separated from the polyprotein by cis cleavage at its respective C-terminus, has been attributed with different functions during potyviral infection of plants. P1 of Turnip mosaic virus (P1-TuMV) harbors an FGSF-motif and FGSL-motif at its N-terminus. This motif is predicted to be a binding site for the host Ras GTPase-activating protein-binding protein (G3BP), which is a key factor for stress granule (SG) formation in mammalian systems and often targeted by viruses to inhibit SG formation. We therefore hypothesized that P1-TuMV might interact with G3BP to control and regulate plant SGs to optimize cellular conditions for the production of viral proteins. Here, we analyzed the co-localization of the Arabidopsis thaliana G3BP-2 with the P1 of two TuMV isolates, namely UK 1 and DEU 2. Surprisingly, P1-TuMV-DEU 2 co-localized with AtG3BP-2 under abiotic stress conditions, whereas P1-TuMV-UK 1 did not. AtG3BP-2::RFP showed strong SGs formation after stress, while P1-UK 1::eGFP maintained a chloroplastic signal under stress conditions, the signal of P1-DEU 2::eGFP co-localized with that of AtG3BP-2::RFP. This indicates a specific interaction between P1-DEU 2 and the AtG3BP family which is not solely based on the canonical interaction motifs.

芜菁花叶病毒 (TuMV)，属于 Potyvirus 属（Potyviridae)，具有很大的宿主范围，由一个单链正链 RNA 基因组组成，编码 12 种蛋白质，包括 P1 蛋白酶。这种通过在其各自的 C 端顺式切割与多蛋白分离的蛋白质在植物的多病毒感染过程中具有不同的功能。芜菁花叶病毒 (P1-TuMV) 的 P1 在其 N 端包含 FGSF 基序和 FGSL 基序。该基序被预测为宿主 Ras GTPase 激活蛋白结合蛋白 (G3BP) 的结合位点，这是哺乳动物系统中应激颗粒 (SG) 形成的关键因素，并且经常被病毒靶向以抑制 SG 形成。因此，我们假设 P1-TuMV 可能与 G3BP 相互作用以控制和调节植物 SG，从而优化细胞条件以生产病毒蛋白。这里，拟南芥G3BP-2 与两个 TuMV 分离株的 P1，即 UK 1 和 DEU 2。令人惊讶的是，P1-TuMV-DEU 2 在非生物胁迫条件下与 AtG3BP-2 共定位，而 P1-TuMV-UK 1 没有。AtG3BP-2::RFP 在应激后显示出强烈的 SGs 形成，而 P1-UK 1::eGFP 在应激条件下保持叶绿体信号，P1-DEU 2::eGFP 的信号与 AtG3BP-2::征求意见稿。这表明 P1-DEU 2 和 AtG3BP 家族之间存在特定的相互作用，这不仅仅是基于规范的相互作用基序。