Buck Institute for Research on Aging, Novato, California, United States of America.
Gladstone Institutes, San Francisco, California, United States of America.
PLoS Pathog. 2022 Sep 12;18(9):e1010811. doi: 10.1371/journal.ppat.1010811. eCollection 2022 Sep.
SARS-CoV-2 non-structural protein Nsp14 is a highly conserved enzyme necessary for viral replication. Nsp14 forms a stable complex with non-structural protein Nsp10 and exhibits exoribonuclease and N7-methyltransferase activities. Protein-interactome studies identified human sirtuin 5 (SIRT5) as a putative binding partner of Nsp14. SIRT5 is an NAD-dependent protein deacylase critical for cellular metabolism that removes succinyl and malonyl groups from lysine residues. Here we investigated the nature of this interaction and the role of SIRT5 during SARS-CoV-2 infection. We showed that SIRT5 interacts with Nsp14, but not with Nsp10, suggesting that SIRT5 and Nsp10 are parts of separate complexes. We found that SIRT5 catalytic domain is necessary for the interaction with Nsp14, but that Nsp14 does not appear to be directly deacylated by SIRT5. Furthermore, knock-out of SIRT5 or treatment with specific SIRT5 inhibitors reduced SARS-CoV-2 viral levels in cell-culture experiments. SIRT5 knock-out cells expressed higher basal levels of innate immunity markers and mounted a stronger antiviral response, independently of the Mitochondrial Antiviral Signaling Protein MAVS. Our results indicate that SIRT5 is a proviral factor necessary for efficient viral replication, which opens novel avenues for therapeutic interventions.
SARS-CoV-2 的非结构蛋白 Nsp14 是一种高度保守的酶，对病毒复制是必需的。Nsp14 与非结构蛋白 Nsp10 形成稳定的复合物，并表现出外切核酸酶和 N7-甲基转移酶活性。蛋白质相互作用研究鉴定出人源 SIRT5（Sirtuin 5）为 Nsp14 的一个假定结合伴侣。SIRT5 是一种 NAD 依赖性蛋白去酰化酶，对于细胞代谢至关重要，它可以从赖氨酸残基上去除琥珀酰基和丙二酰基。在这里，我们研究了这种相互作用的性质以及 SIRT5 在 SARS-CoV-2 感染过程中的作用。我们表明 SIRT5 与 Nsp14 相互作用，但不与 Nsp10 相互作用，这表明 SIRT5 和 Nsp10 是不同复合物的组成部分。我们发现 SIRT5 的催化结构域对于与 Nsp14 的相互作用是必需的，但 Nsp14 似乎不是由 SIRT5 直接去酰化的。此外，在细胞培养实验中，SIRT5 的敲除或使用特定的 SIRT5 抑制剂处理降低了 SARS-CoV-2 的病毒水平。SIRT5 敲除细胞表达更高的基础水平的先天免疫标志物，并独立于线粒体抗病毒信号蛋白 MAVS 产生更强的抗病毒反应。我们的结果表明，SIRT5 是一种促进病毒复制的有利因素，这为治疗干预开辟了新的途径。
