U2AF65 assemblies drive sequence‐specific splice site recognition. (4th July 2019)

• Record Type: Journal Article
• Authors: Tari, Manel; Manceau, Valérie; de Matha Salone, Jean; Kobayashi, Asaki; Pastré, David; Maucuer, Alexandre
• Is Part Of: EMBO reports. Volume 20:Number 8(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-07-04
• Subjects: liquid–liquid phase separation -- RBM39 -- SF3b1 -- splicing -- U2AF2; Molecular biology -- Periodicals; Molecular Biology -- Periodicals; Molecular biology; Periodicals; 572.8
• DOI: 10.15252/embr.201847604
• Languages: English
• ISSNs: 1469-221X

Abstract

Abstract: The essential splicing factor U2AF 65 is known to help anchoring U2 snRNP at the branch site. Its C‐terminal UHM domain interacts with ULM motifs of SF3b155, an U2 snRNP protein. Here, we report a cooperative binding of U2AF 65 and the related protein CAPERα to the multi‐ULM domain of SF3b155. In addition, we show that the RS domain of U2AF 65 drives a liquid–liquid phase separation that is amplified by intronic RNA with repeated pyrimidine tracts. In cells, knockdown of either U2AF 65 or CAPERα improves the inclusion of cassette exons that are preceded by such repeated pyrimidine‐rich motifs. These results support a model in which liquid‐like assemblies of U2AF 65 and CAPERα on repetitive pyrimidine‐rich RNA sequences are driven by their RS domains, and facilitate the recruitment of the multi‐ULM domain of SF3b155. We anticipate that posttranslational modifications and proteins recruited in dynamical U2AF 65 and CAPERα condensates may further contribute to the complex mechanisms leading to specific splice site choice that occurs in cells. Synopsis: The splicing factors U2AF 65 and CAPERα engage multivalent interactions through their low complexity RS domains. The resulting assemblies can bridge the U2snRNP component SF3b155 with repeated polypyrimidine tracts in introns, to promote alternative splicing. U2AF 65 and CAPERα form mixed multiprotein complexes contacting the multi‐ULM domain of SF3b155. The U2AF 65 RS domain drives liquid‐liquid phase separation. U2AF 65 or CAPERα depletion generally reduces exon inclusion, but increases inclusion when cassette exons are preceeded by repeated polypyrimidine tracts that favor the formation of U2AF 65 and CAPERα assemblies in vitro . Abstract : The splicing factors U2AF 65 and CAPERα engage multivalent interactions through their low complexity RS domains. The resulting assemblies can bridge the U2snRNP component SF3b155 with repeated polypyrimidine tracts in introns, to promote alternative splicing.