Ribosome collisions induce mRNA cleavage and ribosome rescue in bacteria
NATURE(2022)
摘要
Ribosome rescue pathways recycle stalled ribosomes and target problematic mRNAs and aborted proteins for degradation 1 , 2 . In bacteria, it remains unclear how rescue pathways distinguish ribosomes stalled in the middle of a transcript from actively translating ribosomes 3 – 6 . Here, using a genetic screen in Escherichia coli , we discovered a new rescue factor that has endonuclease activity. SmrB cleaves mRNAs upstream of stalled ribosomes, allowing the ribosome rescue factor tmRNA (which acts on truncated mRNAs 3 ) to rescue upstream ribosomes. SmrB is recruited to ribosomes and is activated by collisions. Cryo-electron microscopy structures of collided disomes from E. coli and Bacillus subtilis show distinct and conserved arrangements of individual ribosomes and the composite SmrB-binding site. These findings reveal the underlying mechanisms by which ribosome collisions trigger ribosome rescue in bacteria.
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关键词
Cryoelectron microscopy,Ribosome,Science,Humanities and Social Sciences,multidisciplinary
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