title: SUS1 introns are required for efficient mRNA nuclear export in yeast.
abstract: Efficient coupling between mRNA synthesis and export is essential for gene expression. Sus1/ENY2, a component of the SAGA and TREX-2 complexes, is involved in both transcription and mRNA export. While most yeast genes lack introns, we previously reported that yeast SUS1 bears two. Here we show that this feature is evolutionarily conserved and critical for Sus1 function. We determine that while SUS1 splicing is inefficient, it responds to cellular conditions, and intronic mutations either promoting or blocking splicing lead to defects in mRNA export and cell growth. Consistent with this, we find that an intron-less SUS1 only partially rescues sus1Δ phenotypes. Remarkably, splicing of each SUS1 intron is also affected by the presence of the other and by SUS1 exonic sequences. Moreover, by following SUS1 RNA and protein levels we establish that nonsense-mediated decay (NMD) pathway and the splicing factor Mud2 both play a role in SUS1 expression. Our data (and those of the accompanying work by Hossain et al.) provide evidence of the involvement of splicing, translation, and decay in the regulation of early events in mRNP biogenesis; and imply the additional requirement for a balance in splicing isoforms from a single gene.
authors.affiliation: Centro de Investigación Príncipe Felipe, Gene Expression coupled to RNA Transport Laboratory, Av Saler 16. E-46012, Valencia, Spain.
authors.forename: Bernardo
authors.initials: B
authors.lastname: Cuenca-Bono
authors.forename: Varinia
authors.initials: V
authors.lastname: García-Molinero
authors.forename: Pau
authors.initials: P
authors.lastname: Pascual-García
authors.forename: Hernan
authors.initials: H
authors.lastname: Dopazo
authors.forename: Ana
authors.initials: A
authors.lastname: Llopis
authors.forename: Josep
authors.initials: J
authors.lastname: Vilardell
authors.forename: Susana
authors.initials: S
authors.lastname: Rodríguez-Navarro
mesh_terms: D021581:Active Transport, Cell Nucleus; D002467:Cell Nucleus / Q000378:metabolism*; D019143:Evolution, Molecular; D005091:Exons; D015966:Gene Expression Regulation, Fungal; D007438:Introns; D059365:Nonsense Mediated mRNA Decay; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D009687:Nuclear Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; C481300:Sus1 protein, S cerevisiae