title: Major phosphorylation of SF1 on adjacent Ser-Pro motifs enhances interaction with U2AF65.
abstract: Protein phosphorylation ensures the accurate and controlled expression of the genome, for instance by regulating the activities of pre-mRNA splicing factors. Here we report that splicing factor 1 (SF1), which is involved in an early step of intronic sequence recognition, is highly phosphorylated in mammalian cells on two serines within an SPSP motif at the junction between its U2AF65 and RNA binding domains. We show that SF1 interacts in vitro with the protein kinase KIS, which possesses a 'U2AF homology motif' (UHM) domain. The UHM domain of KIS is required for KIS and SF1 to interact, and for KIS to efficiently phosphorylate SF1 on the SPSP motif. Importantly, SPSP phosphorylation by KIS increases binding of SF1 to U2AF65, and enhances formation of the ternary SF1-U2AF65-RNA complex. These results further suggest that this phosphorylation event has an important role for the function of SF1, and possibly for the structural rearrangements associated with spliceosome assembly and function.
authors.affiliation: INSERM, U706, UPMC, Institut du Fer à Moulin, Paris, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Manceau
authors.forename: Matthew
authors.initials: M
authors.lastname: Swenson
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Le Caer
authors.forename: André
authors.initials: A
authors.lastname: Sobel
authors.forename: Clara L
authors.initials: CL
authors.lastname: Kielkopf
authors.forename: Alexandre
authors.initials: A
authors.lastname: Maucuer
mesh_terms: D020816:Amino Acid Motifs / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D066298:In Vitro Techniques; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011392:Proline / Q000378:metabolism*; D011485:Protein Binding; D012313:RNA / Q000378:metabolism; D000072260:RNA Splicing Factors; D012261:Ribonucleoproteins / Q000378:metabolism*; D012694:Serine / Q000378:metabolism*; D000072668:Splicing Factor U2AF; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D000072260:RNA Splicing Factors; D012261:Ribonucleoproteins; C107467:SF1 protein, human; D000072668:Splicing Factor U2AF; D014157:Transcription Factors; C000607494:U2AF2 protein, human; D012694:Serine; D012313:RNA; D011392:Proline