Structural mechanism of angiogenin activation by the ribosome

• 成果类型: Article
• 署名作者: Loveland, Anna B.; Koh, Cha San; Ganesan, Robin; Jacobson, Allan; Korostelev, Andrei A.
• 署名单位: University of Massachusetts System; UMass Chan Medical School; University of Massachusetts Worcester; University of Massachusetts System; UMass Chan Medical School; University of Massachusetts Worcester
• 刊物名称: Nature
• ISSN/ISSBN: 0028-4521
• DOI: 10.1038/s41586-024-07508-8
• 发表日期: 2024-06-20
• 关键词: real-space refinement; high-level expression; induced up-regulation; transfer-rna; ribonucleolytic activity; escherichia-coli; crystal-structure; cryo-em; protein; yeast

摘要

Angiogenin, an RNase-A-family protein, promotes angiogenesis and has been implicated in cancer, neurodegenerative diseases and epigenetic inheritance1-10. After activation during cellular stress, angiogenin cleaves tRNAs at the anticodon loop, resulting in translation repression11-15. However, the catalytic activity of isolated angiogenin is very low, and the mechanisms of the enzyme activation and tRNA specificity have remained a puzzle3,16-23. Here we identify these mechanisms using biochemical assays and cryogenic electron microscopy (cryo-EM). Our study reveals that the cytosolic ribosome is the activator of angiogenin. A cryo-EM structure features angiogenin bound in the A site of the 80S ribosome. The C-terminal tail of angiogenin is rearranged by interactions with the ribosome to activate the RNase catalytic centre, making the enzyme several orders of magnitude more efficient in tRNA cleavage. Additional 80S-angiogenin structures capture how tRNA substrate is directed by the ribosome into angiogenin's active site, demonstrating that the ribosome acts as the specificity factor. Our findings therefore suggest that angiogenin is activated by ribosomes with a vacant A site, the abundance of which increases during cellular stress24-27. These results may facilitate the development of therapeutics to treat cancer and neurodegenerative diseases. Angiogenin binds to the ribosomal A site to cleave tRNA.