National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
R01 GM127094
米国
引用
ジャーナル: Nature / 年: 2024 タイトル: Structural mechanism of angiogenin activation by the ribosome. 著者: Anna B Loveland / Cha San Koh / Robin Ganesan / Allan Jacobson / Andrei A Korostelev / 要旨: Angiogenin, an RNase-A-family protein, promotes angiogenesis and has been implicated in cancer, neurodegenerative diseases and epigenetic inheritance. After activation during cellular stress, ...Angiogenin, an RNase-A-family protein, promotes angiogenesis and has been implicated in cancer, neurodegenerative diseases and epigenetic inheritance. After activation during cellular stress, angiogenin cleaves tRNAs at the anticodon loop, resulting in translation repression. However, the catalytic activity of isolated angiogenin is very low, and the mechanisms of the enzyme activation and tRNA specificity have remained a puzzle. 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 stress. These results may facilitate the development of therapeutics to treat cancer and neurodegenerative diseases.