Center for Immune-Related Diseases at Shanghai Institute of Immunology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Department of Immunology and Microbiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
PLoS Pathog. 2022 Apr 28;18(4):e1010504. doi: 10.1371/journal.ppat.1010504. eCollection 2022 Apr.
RSK1, an essential cellular kinase for Kaposi's sarcoma-associated herpesvirus (KSHV) replication, is highly phosphorylated and SUMOylated during KSHV lytic cycle, which determine the substrate phosphorylation and specificity of RSK1, respectively. However, the SUMO E3 ligase responsible for attaching SUMO to RSK1 has not yet been identified. By genome-wide screening, we found that KSHV ORF45 is necessary and sufficient to enhance RSK1 SUMOylation. Mechanistically, KSHV ORF45 binds to SUMOs via two classic SUMO-interacting motifs (SIMs) and functions as a SIM-dependent SUMO E3 ligase for RSK1. Mutations on these ORF45 SIMs resulted in much lower lytic gene expressions, viral DNA replication, and mature progeny virus production. Interestingly, KSHV ORF45 controls RSK1 SUMOylation and phosphorylation via two separated functional regions: SIMs and amino acid 17-90, respectively, which do not affect each other. Similar to KSHV ORF45, ORF45 of Rhesus Macaque Rhadinovirus has only one SIM and also increases RSK1 SUMOylation in a SIM-dependent manner, while other ORF45 homologues do not have this function. Our work characterized ORF45 as a novel virus encoded SUMO E3 ligase, which is required for ORF45-RSK1 axis-mediated KSHV lytic gene expression.
RSK1 是卡波西肉瘤相关疱疹病毒 (KSHV) 复制所必需的细胞激酶，在 KSHV 裂解周期中高度磷酸化和 SUMO 化，分别决定了 RSK1 的底物磷酸化和特异性。然而，负责将 SUMO 连接到 RSK1 的 SUMO E3 连接酶尚未被鉴定。通过全基因组筛选，我们发现 KSHV ORF45 是增强 RSK1 SUMO 化所必需和充分的。在机制上，KSHV ORF45 通过两个经典的 SUMO 相互作用基序 (SIM) 与 SUMO 结合，并作为 RSK1 的 SIM 依赖性 SUMO E3 连接酶发挥作用。这些 ORF45 SIM 上的突变导致裂解基因表达、病毒 DNA 复制和成熟子代病毒产生的水平显著降低。有趣的是，KSHV ORF45 通过两个独立的功能区域控制 RSK1 SUMO 化和磷酸化：SIMs 和氨基酸 17-90，它们彼此之间不影响。类似于 KSHV ORF45，恒河猴疱疹病毒的 ORF45 只有一个 SIM，也以 SIM 依赖的方式增加 RSK1 SUMO 化，而其他 ORF45 同源物则没有此功能。我们的工作将 ORF45 表征为一种新型病毒编码的 SUMO E3 连接酶，该酶是 ORF45-RSK1 轴介导的 KSHV 裂解基因表达所必需的。
