Nuclear transit of the RNA-binding protein She2 is required for translational control of localized ASH1 mRNA.
Cytoplasmic localization and localized translation of messenger RNAs contribute to asymmetrical protein distribution. Recognition of localized mRNAs by RNA-binding proteins can occur in the cytoplasm or, alternatively, co- or post-transcriptionally in the nucleus. In budding yeast, mRNAs destined for localization are bound by the She2 protein before their nuclear export. Here, we show that a specific transcript, known as ASH1 mRNA, and She2 localize specifically to the nucleolus when their nuclear export is blocked. Nucleolar She2 localization is enhanced in a She2 mutant that cannot bind to RNA. A fusion protein of the amino terminus of She3 and She2 (She3N-She2) fails to enter the nucleus, but does not impair ASH1 mRNA localization. Instead, these cells fail to distribute Ash1 protein asymmetrically, which is caused by a defective translational control of ASH1 mRNA. Our results indicate that the nucleolar transit of RNA-binding proteins such as She2 is necessary for the correct assembly of translationally silenced localizing messenger ribonucleoproteins.
Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany.
Tung-Gia
TG
Du
Stephan
S
Jellbauer
Marisa
M
Müller
Maria
M
Schmid
Dierk
D
Niessing
Ralf-Peter
RP
Jansen
D001692:Biological Transport; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D047468:Immunoprecipitation; D008856:Microscopy, Fluorescence; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013696:Temperature
C098733:ASH1 protein, S cerevisiae; D004268:DNA-Binding Proteins; C443676:HEK2 protein, S cerevisiae; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D012261:Ribonucleoproteins; C471175:SHE2 protein, S cerevisiae; C471176:SHE3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins