Structural elements required for the localization of ASH1 mRNA and of a green fluorescent protein reporter particle in vivo.
The sorting of the Ash1 protein to the daughter nucleus of Saccharomyces cerevisiae in late anaphase of the budding cycle correlates with the localization of ASH1 mRNA at the bud tip [1] [2]. Although the 3' untranslated region (3' UTR) of ASH1 is sufficient to localize a reporter mRNA, it is not necessary, a result which indicates that other sequences are involved [1]. We report the identification of three additional cis-acting elements in the coding region. Each element alone, when fused to a lacZ reporter gene, was sufficient for the localization of the lacZ mRNA reporter to the bud. A fine-structure analysis of the 3' UTR element showed that its function in mRNA localization did not depend on a specific sequence but on the secondary and tertiary structure of a minimal 118 nucleotide stem-loop. Mutations in the stem-loop that affect the localization of the lacZ mRNA reporter also affected the formation of the localization particles, in living cells, composed of a green fluorescent protein (GFP) complexed with lacZ-ASH1-3' UTR mRNA [3]. A specific stem-loop in the 3' UTR of the ASH1 mRNA is therefore required for both localization and particle formation, suggesting that complex formation is part of the localization mechanism. An analysis on one of the coding-region elements revealed a comparable stem-loop structure with similar functional requirements.
Chartrand
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Departments of Anatomy and Structural Biology and Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.
Meng
X H
XH
Singer
R H
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Long
R M
RM
D020413:3' Untranslated Regions / Q000235:genetics / Q000502:physiology*; D000705:Anaphase; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D016764:Cell Polarity; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000235:genetics*; D017930:Genes, Reporter; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000235:genetics; D012331:RNA, Fungal / Q000737:chemistry* / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D013045:Species Specificity; D013329:Structure-Activity Relationship; D013489:Suppression, Genetic; D014157:Transcription Factors / Q000235:genetics*; D014170:Transformation, Genetic
D020413:3' Untranslated Regions; C098733:ASH1 protein, S cerevisiae; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors