An exclusively nuclear RNA-binding protein affects asymmetric localization of ASH1 mRNA and Ash1p in yeast.
The localization of ASH1 mRNA to the distal tip of budding yeast cells is essential for the proper regulation of mating type switching in Saccharomyces cerevisiae. A localization element that is predominantly in the 3'-untranslated region (UTR) can direct this mRNA to the bud. Using this element in the three-hybrid in vivo RNA-binding assay, we identified a protein, Loc1p, that binds in vitro directly to the wild-type ASH1 3'-UTR RNA, but not to a mutant RNA incapable of localizing to the bud nor to several other mRNAs. LOC1 codes for a novel protein that recognizes double-stranded RNA structures and is required for efficient localization of ASH1 mRNA. Accordingly, Ash1p gets symmetrically distributed between daughter and mother cells in a loc1 strain. Surprisingly, Loc1p was found to be strictly nuclear, unlike other known RNA-binding proteins involved in mRNA localization which shuttle between the nucleus and the cytoplasm. We propose that efficient cytoplasmic ASH1 mRNA localization requires a previous interaction with specific nuclear factors.
Long
R M
RM
Medical College of Wisconsin, Department of Microbiology and Molecular Genetics, Milwaukee, Wisconsin 53226, USA. rlong@mcw.edu
Gu
W
W
Meng
X
X
Gonsalvez
G
G
Singer
R H
RH
Chartrand
P
P
D020413:3' Untranslated Regions; D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000378:metabolism*; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D017930:Genes, Reporter / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids; D011233:Precipitin Tests; D021381:Protein Transport / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D020413:3' Untranslated Regions; C098733:ASH1 protein, S cerevisiae; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C426224:LOC1 protein, S cerevisiae; C077734:NPL3 protein, S cerevisiae; D009687:Nuclear Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors