The post-translational modification of proteins by SUMO is crucial for cellular viability and mammalian development in part due to the contribution of SUMOylation to genome duplication and repair. To investigate the mechanisms underpinning the essential function of SUMO, we undertook a genome-scale CRISPR/Cas9 screen probing the response to SUMOylation inhibition. This effort identified 130 genes whose disruption reduces or enhances the toxicity of TAK-981, a clinical-stage inhibitor of the SUMO E1-activating enzyme. Among the strongest hits, we validated and characterized NFATC2IP, an evolutionarily conserved protein related to the fungal Esc2 and Rad60 proteins that harbors tandem SUMO-like domains. Cells lacking NFATC2IP are viable but are hypersensitive to SUMO E1 inhibition, likely due to the accumulation of mitotic chromosome bridges and micronuclei. NFATC2IP primarily acts in interphase and associates with nascent DNA, suggesting a role in the postreplicative resolution of replication or recombination intermediates. Mechanistically, NFATC2IP interacts with the SMC5/6 complex and UBC9, the SUMO E2, via its first and second SUMO-like domains, respectively. AlphaFold-Multimer modeling suggests that NFATC2IP positions and activates the UBC9–NSMCE2 complex, the SUMO E3 ligase associated with SMC5/SMC6. We conclude that NFATC2IP is a key mediator of SUMO-dependent genomic integrity that collaborates with the SMC5/6 complex.

中文翻译：

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NFATC2IP 是 SUMO 依赖性基因组完整性的中介者

SUMO 对蛋白质的翻译后修饰对于细胞活力和哺乳动物发育至关重要，部分原因是 SUMO 化对基因组复制和修复的贡献。为了研究支撑 SUMO 基本功能的机制，我们进行了基因组规模的 CRISPR/Cas9 筛选，探讨对 SUMO 化抑制的反应。这项工作确定了 130 个基因，这些基因的破坏可降低或增强 TAK-981（SUMO E1 激活酶的临床阶段抑制剂）的毒性。在最热门的产品中，我们验证并表征了 NFATC2IP，这是一种与真菌 Esc2 和 Rad60 蛋白相关的进化保守蛋白，具有串联的 SUMO 样结构域。缺乏 NFATC2IP 的细胞是可行的，但对 SUMO E1 抑制非常敏感，可能是由于有丝分裂染色体桥和微核的积累。 NFATC2IP 主要作用于间期并与新生 DNA 相关，表明在复制或重组中间体的复制后解析中发挥作用。从机制上讲，NFATC2IP 分别通过其第一个和第二个类 SUMO 结构域与 SMC5/6 复合体和 UBC9（SUMO E2）相互作用。 AlphaFold-Multimer 模型表明，NFATC2IP 定位并激活 UBC9-NSMCE2 复合物，即与 SMC5/SMC6 相关的 SUMO E3 连接酶。我们得出的结论是，NFATC2IP 是 SUMO 依赖性基因组完整性的关键介质，与 SMC5/6 复合体合作。