title: Protein arginine methylation of Npl3 promotes splicing of the SUS1 intron harboring non-consensus 5' splice site and branch site.
abstract: Protein arginine methylation occurs on spliceosomal components and spliceosome-associated proteins, but how this modification contributes to their function in pre-mRNA splicing remains sparse. Here we provide evidence that protein arginine methylation of the yeast SR-/hnRNP-like protein Npl3 plays a role in facilitating efficient splicing of the SUS1 intron that harbors a non-consensus 5' splice site and branch site. In yeast cells lacking the major protein arginine methyltransferase HMT1, we observed a change in the co-transcriptional recruitment of the U1 snRNP subunit Snp1 and Npl3 to pre-mRNAs harboring both consensus (ECM33 and ASC1) and non-consensus (SUS1) 5' splice site and branch site. Using an Npl3 mutant that phenocopies wild-type Npl3 when expressed in Δhmt1 cells, we showed that the arginine methylation of Npl3 is responsible for this. Examination of pre-mRNA splicing efficiency in these mutants reveals the requirement of Npl3 methylation for the efficient splicing of SUS1 intron 1, but not of ECM33 or ASC1. Changing the 5' splice site and branch site in SUS1 intron 1 to the consensus form restored splicing efficiency in an Hmt1-independent manner. Results from biochemical studies show that methylation of Npl3 promotes its optimal association with the U1 snRNP through its association with the U1 snRNP subunit Mud1. Based on these data, we propose a model in which Hmt1, via arginine methylation of Npl3, facilitates U1 snRNP engagement with the pre-mRNA to promote usage of non-consensus splice sites by the splicing machinery.
authors.affiliation: Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY, United States.
authors.forename: Bhavana
authors.initials: B
authors.lastname: Muddukrishna
authors.affiliation: Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY, United States.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Jackson
authors.affiliation: Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY, United States. Electronic address: mcyu@buffalo.edu.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Yu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D001120:Arginine / Q000235:genetics / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D007438:Introns; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008745:Methylation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011484:Protein-Arginine N-Methyltransferases / Q000235:genetics / Q000378:metabolism; D012326:RNA Splicing / Q000502:physiology*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C111825:ASC1 protein, S cerevisiae; D048868:Adaptor Proteins, Signal Transducing; C497117:ECM33 protein, S cerevisiae; D008565:Membrane Proteins; C077734:NPL3 protein, S cerevisiae; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; C481300:Sus1 protein, S cerevisiae; D001120:Arginine; C475182:HMT1 protein, S cerevisiae; D011484:Protein-Arginine N-Methyltransferases; D019204:GTP-Binding Proteins
keywords: Hmt1; Npl3; Pre-mRNA splicing; Protein arginine methylation; U1 snRNP