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Nat Struct Mol Biol. 2017 May;24(5):453-460. doi: 10.1038/nsmb.3396. Epub 2017 Apr 3.

Structure of the 40S-ABCE1 post-splitting complex in ribosome recycling and translation initiation.

Author information

1
Gene Center and Center of Integrated Protein Science Munich, Department of Biochemistry, University of Munich, Munich, Germany.
2
Institute of Biochemistry, Biocenter, Goethe University, Frankfurt/Main, Germany.
3
Institute for Molecular Genetics and Cellular Microbiology, Biocenter, Goethe University, Frankfurt/Main, Germany.

Abstract

The essential ATP-binding cassette protein ABCE1 splits 80S ribosomes into 60S and 40S subunits after canonical termination or quality-control-based mRNA surveillance processes. However, the underlying splitting mechanism remains enigmatic. Here, we present a cryo-EM structure of the yeast 40S-ABCE1 post-splitting complex at 3.9-Å resolution. Compared to the pre-splitting state, we observe repositioning of ABCE1's iron-sulfur cluster domain, which rotates 150° into a binding pocket on the 40S subunit. This repositioning explains a newly observed anti-association activity of ABCE1. Notably, the movement implies a collision with A-site factors, thus explaining the splitting mechanism. Disruption of key interactions in the post-splitting complex impairs cellular homeostasis. Additionally, the structure of a native post-splitting complex reveals ABCE1 to be part of the 43S initiation complex, suggesting a coordination of termination, recycling, and initiation.

PMID:
28368393
DOI:
10.1038/nsmb.3396
[Indexed for MEDLINE]

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