title: The pre-mRNA retention and splicing complex controls expression of the Mediator subunit Med20.
abstract: The heterotrimeric pre-mRNA retention and splicing (RES) complex, consisting of Bud13p, Snu17p and Pml1p, promotes splicing and nuclear retention of a subset of intron-containing pre-mRNAs. Yeast cells deleted for individual RES genes show growth defects that are exacerbated at elevated temperatures. Although the growth phenotypes correlate to the splicing defects in the individual mutants, the underlying mechanism is unknown. Here, we show that the temperature sensitive (Ts) growth phenotype of bud13Δ and snu17Δ cells is a consequence of inefficient splicing of MED20 pre-mRNA, which codes for a subunit of the Mediator complex; a co-regulator of RNA polymerase II transcription. The MED20 pre-mRNA splicing defect is less pronounced in pml1Δ cells, explaining why they grow better than the other 2 RES mutants at elevated temperatures. Inactivation of the cytoplasmic nonsense-mediated mRNA decay (NMD) pathway in the RES mutants leads to accumulation of MED20 pre-mRNA, indicating that inefficient nuclear retention contributes to the growth defect. Further, the Ts phenotype of bud13Δ and snu17Δ cells is partially suppressed by the inactivation of NMD, showing that the growth defects are augmented by the presence of a functional NMD pathway. Collectively, our results demonstrate an important role of the RES complex in maintaining the Med20p levels.
authors.affiliation: a Department of Molecular Biology , Umeå University , Umeå , Sweden.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: a Department of Molecular Biology , Umeå University , Umeå , Sweden.|b BRF Krutet , Norra Majorsgatan, Umeå , Sweden.|c University of Tartu, Institute of Technology , Nooruse, Tartu , Estonia.
authors.forename: Marcus J O
authors.initials: MJO
authors.lastname: Johansson
mesh_terms: D002352:Carrier Proteins / Q000235:genetics; D017353:Gene Deletion; D056892:Mediator Complex / Q000235:genetics* / Q000378:metabolism; D059365:Nonsense Mediated mRNA Decay; D012322:RNA Precursors / Q000235:genetics*; D012326:RNA Splicing; D017413:Ribonucleoprotein, U2 Small Nuclear / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D013696:Temperature
chemical_list: C534389:Bud13 protein, S cerevisiae; D002352:Carrier Proteins; C425663:IST3 protein, S cerevisiae; D056892:Mediator Complex; D012322:RNA Precursors; D017413:Ribonucleoprotein, U2 Small Nuclear; C074748:SRB2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins
keywords: Med20; NMD; RES complex; mediator; splicing