Institute of Molecular Biology (IMB), Mainz, Germany.
Nat Commun. 2023 Dec 15;14(1):8363. doi: 10.1038/s41467-023-44096-z.
Selective protein degradation typically involves substrate recognition via short linear motifs known as degrons. Various degrons can be found at protein termini from bacteria to mammals. While N-degrons have been extensively studied, our understanding of C-degrons is still limited. Towards a comprehensive understanding of eukaryotic C-degron pathways, here we perform an unbiased survey of C-degrons in budding yeast. We identify over 5000 potential C-degrons by stability profiling of random peptide libraries and of the yeast C‑terminome. Combining machine learning, high-throughput mutagenesis and genetic screens reveals that the SCF ubiquitin ligase targets ~40% of degrons using a single F-box substrate receptor Das1. Although sequence-specific, Das1 is highly promiscuous, recognizing a variety of C-degron motifs. By screening for full-length substrates, we implicate SCF in degradation of orphan protein complex subunits. Altogether, this work highlights the variety of C-degron pathways in eukaryotes and uncovers how an SCF/C-degron pathway of broad specificity contributes to proteostasis.
选择性蛋白质降解通常涉及通过短线性基序（称为降解基序）识别底物。从细菌到哺乳动物的各种蛋白质末端都可以找到降解基序。虽然 N 降解基序已经得到了广泛研究，但我们对 C 降解基序的理解仍然有限。为了全面了解真核生物 C 降解基序途径，我们在 budding yeast 中进行了 C 降解基序的无偏调查。我们通过随机肽文库和酵母 C 端组的稳定性分析鉴定了超过 5000 个潜在的 C 降解基序。结合机器学习、高通量诱变和遗传筛选，揭示了 SCF 泛素连接酶使用单个 F-box 底物受体 Das1 靶向约 40%的降解基序。尽管具有序列特异性，但 Das1 高度混杂，可识别各种 C 降解基序。通过筛选全长底物，我们将 SCF 与孤儿蛋白复合物亚基的降解联系起来。总的来说，这项工作突出了真核生物中 C 降解基序途径的多样性，并揭示了广泛特异性的 SCF/C 降解基序途径如何有助于蛋白质稳态。
