Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093.
Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093
Proc Natl Acad Sci U S A. 2020 Apr 7;117(14):7950-7960. doi: 10.1073/pnas.1918417117. Epub 2020 Mar 19.
Intracellular pathogen infection leads to proteotoxic stress in host organisms. Previously we described a physiological program in the nematode called the intracellular pathogen response (IPR), which promotes resistance to proteotoxic stress and appears to be distinct from canonical proteostasis pathways. The IPR is controlled by PALS-22 and PALS-25, proteins of unknown biochemical function, which regulate expression of genes induced by natural intracellular pathogens. We previously showed that PALS-22 and PALS-25 regulate the mRNA expression of the predicted ubiquitin ligase component cullin , which promotes thermotolerance in mutants. However, it was unclear whether CUL-6 acted alone, or together with other cullin-ring ubiquitin ligase components, which comprise a greatly expanded gene family in Here we use coimmunoprecipitation studies paired with genetic analysis to define the cullin-RING ligase components that act together with CUL-6 to promote thermotolerance. First, we identify a previously uncharacterized RING domain protein in the TRIM family we named RCS-1, which acts as a core component with CUL-6 to promote thermotolerance. Next, we show that the Skp-related proteins SKR-3, SKR-4, and SKR-5 act redundantly to promote thermotolerance with CUL-6. Finally, we screened F-box proteins that coimmunoprecipitate with CUL-6 and find that FBXA-158 and FBXA-75 promote thermotolerance. In summary, we have defined the three core components and two F-box adaptors of a cullin-RING ligase complex that promotes thermotolerance as part of the IPR in , which adds to our understanding of how organisms cope with proteotoxic stress.
细胞内病原体感染会导致宿主生物产生蛋白毒性应激。此前我们描述了线虫中一种称为细胞内病原体反应 (IPR) 的生理程序，该程序促进了对蛋白毒性应激的抗性，并且似乎与经典的蛋白稳定途径不同。IPR 由 PALS-22 和 PALS-25 控制，这两种蛋白质的生化功能未知，它们调节天然细胞内病原体诱导的基因表达。我们之前表明，PALS-22 和 PALS-25 调节预测的泛素连接酶成分 cullin 的 mRNA 表达 ，这促进了 突变体的耐热性。然而，尚不清楚 CUL-6 是否单独起作用，还是与其他 cullin 环泛素连接酶成分一起起作用，后者在 中构成一个大大扩展的基因家族。在这里，我们使用共免疫沉淀研究与遗传分析相结合，定义了与 CUL-6 一起起作用以促进耐热性的 cullin-RING 连接酶成分。首先，我们在 TRIM 家族中鉴定出一种以前未表征的 RING 结构域蛋白，我们将其命名为 RCS-1，它作为与 CUL-6 一起起作用的核心成分促进耐热性。接下来，我们表明 Skp 相关蛋白 SKR-3、SKR-4 和 SKR-5 与 CUL-6 一起冗余地发挥作用以促进耐热性。最后，我们筛选与 CUL-6 共免疫沉淀的 F-box 蛋白，发现 FBXA-158 和 FBXA-75 促进耐热性。总之，我们已经定义了促进耐热性的 cullin-RING 连接酶复合物的三个核心成分和两个 F-box 接头，这是 IPR 的一部分，增加了我们对生物体如何应对蛋白毒性应激的理解。
