Fip1 is a multivalent interaction scaffold for processing factors in human mRNA 3' end biogenesis
- University of Zurich, Switzerland
Abstract
3' end formation of most eukaryotic mRNAs is dependent on the assembly of a ~1.5 megadalton multiprotein complex, that catalyzes the coupled reaction of pre-mRNA cleavage and polyadenylation. In mammals, the cleavage and polyadenylation specificity factor (CPSF) constitutes the core of the 3' end processing machinery onto which the remaining factors, including cleavage stimulation factor (CstF) and poly(A) polymerase (PAP), assemble. These interactions are mediated by Fip1, a CPSF subunit characterized by high degree of intrinsic disorder. Here, we report two crystal structures revealing the interactions of human Fip1 (hFip1) with CPSF30 and CstF77. We demonstrate that CPSF contains two copies of hFip1, each binding to the zinc finger (ZF) domains 4 and 5 of CPSF30. Using polyadenylation assays we show that the two hFip1 copies are functionally redundant in recruiting one copy of PAP, thereby increasing the processivity of RNA polyadenylation. We further show that the interaction between hFip1 and CstF77 is mediated via a short motif in the N-terminal 'acidic' region of hFip1. In turn, CstF77 competitively inhibits CPSF-dependent PAP recruitment and 3' polyadenylation. Taken together, these results provide a structural basis for the multivalent scaffolding and regulatory functions of hFip1 in 3' end processing.
Data availability
X-ray diffraction data (atomic coordinates and structure factors) have been submitted to the PDB and will be released upon publication.
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Crystal structure of human CPSF30 in complex with hFip1Protein Data Bank ID: 7ZYH.
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Crystal structure of human CstF77 in complex with hFip1Protein Data Bank ID: 7ZY4.
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Cryo-EM structure of human CPSF160-WDR33-CPSF30-PAS RNA-CstF77 complexPotein Data Bank ID: 6URO.
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Cryo-EM structure of human CPSF160-WDR33-CPSF30-PAS RNA-CstF77 complexElectron Microscopy Data Bank ID: EMD-20861.
Article and author information
Author details
Funding
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (NCCR RNA and Disease)
- Martin Jinek
Boehringer Ingelheim Fonds
- Lena Maria Muckenfuss
Howard Hughes Medical Institute (55008735)
- Martin Jinek
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2022, Muckenfuss et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Fip1 is a multivalent interaction scaffold for processing factors in human mRNA 3' end biogenesis
eLife 11:e80332.
https://doi.org/10.7554/eLife.80332
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