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Proc Natl Acad Sci U S A. 2018 Feb 13;115(7):E1419-E1428. doi: 10.1073/pnas.1718723115. Epub 2017 Dec 5.

Molecular basis for the recognition of the human AAUAAA polyadenylation signal.

Author information

1
Department of Biological Sciences, Columbia University, New York, NY 10027.
2
Laboratory of Molecular Electron Microscopy, Rockefeller University, New York, NY 10065.
3
Department of Biological Sciences, Columbia University, New York, NY 10027; jlm2@columbia.edu twalz@mail.rockefeller.edu ltong@columbia.edu.
4
Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697.
5
Laboratory of Molecular Electron Microscopy, Rockefeller University, New York, NY 10065; jlm2@columbia.edu twalz@mail.rockefeller.edu ltong@columbia.edu.

Abstract

Nearly all eukaryotic messenger RNA precursors must undergo cleavage and polyadenylation at their 3'-end for maturation. A crucial step in this process is the recognition of the AAUAAA polyadenylation signal (PAS), and the molecular mechanism of this recognition has been a long-standing problem. Here, we report the cryo-electron microscopy structure of a quaternary complex of human CPSF-160, WDR33, CPSF-30, and an AAUAAA RNA at 3.4-Å resolution. Strikingly, the AAUAAA PAS assumes an unusual conformation that allows this short motif to be bound directly by both CPSF-30 and WDR33. The A1 and A2 bases are recognized specifically by zinc finger 2 (ZF2) of CPSF-30 and the A4 and A5 bases by ZF3. Interestingly, the U3 and A6 bases form an intramolecular Hoogsteen base pair and directly contact WDR33. CPSF-160 functions as an essential scaffold and preorganizes CPSF-30 and WDR33 for high-affinity binding to AAUAAA. Our findings provide an elegant molecular explanation for how PAS sequences are recognized for mRNA 3'-end formation.

KEYWORDS:

RNA recognition; WD40 domains; polyadenylation; pre-mRNA 3′-end processing; zinc finger

PMID:
29208711
PMCID:
PMC5816196
DOI:
10.1073/pnas.1718723115
[Indexed for MEDLINE]
Free PMC Article

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