Nuclear retention of unspliced mRNAs in yeast is mediated by perinuclear Mlp1.
The molecular mechanism underlying the retention of intron-containing mRNAs in the nucleus is not understood. Here, we show that retention of intron-containing mRNAs in yeast is mediated by perinuclearly located Mlp1. Deletion of MLP1 impairs retention while having no effect on mRNA splicing. The Mlp1-dependent leakage of intron-containing RNAs is increased in presence of ts-prp18 delta, a splicing mutant. When overall pre-mRNA levels are increased by deletion of RRP6, a nuclear exosome component, MLP1 deletion augments leakage of only the intron-containing portion of mRNAs. Our data suggest, moreover, that Mlp1-dependent retention is mediated via the 5' splice site. Intriguingly, we found Mlp-proteins to be present only on sections of the NE adjacent to chromatin. We propose that at this confined site the perinuclear Mlp1 implements a quality control step prior to export, physically retaining faulty pre-mRNAs.
Pubmed ID: 14718167 RIS Download
Active Transport, Cell Nucleus | Cell Nucleus | Exoribonucleases | Exosome Multienzyme Ribonuclease Complex | Introns | Mutation | Nuclear Envelope | Nuclear Pore Complex Proteins | Nuclear Proteins | Protein Transport | RNA Splice Sites | RNA Splicing | RNA, Messenger | Ribonucleoprotein, U5 Small Nuclear | Saccharomyces cerevisiae Proteins | Yeasts