Cotranscriptional recruitment of She2p by RNA pol II elongation factor Spt4-Spt5/DSIF promotes mRNA localization to the yeast bud.
Pre-mRNA processing is coupled with transcription. It is still unclear if the transcription machinery can also directly affect the cytoplasmic fate of a transcript, such as its intracellular localization. In yeast, the RNA-binding protein She2p binds several mRNAs and targets them for localization at the bud. Here we report that She2p is recruited cotranscriptionally to the nascent bud-localized ASH1, IST2, and EAR1 mRNA. She2p interacts in vivo with the elongating forms of RNA polymerase II (pol II) via the transcription elongation factor Spt4-Spt5. Mutations in either SPT4 or SPT5 reduce the cotranscriptional recruitment of She2p on the ASH1 gene, disrupt the proper localization of ASH1 mRNA at the bud tip, and affect Ash1p sorting to the daughter cell nucleus. We propose that She2p is recruited by the RNA pol II machinery prior to its transfer to nascent bud-localized mRNAs. Indeed, She2p is present with RNA pol II on genes coding for localized or nonlocalized transcripts, but is associated with nascent mRNA only on genes coding for bud-localized transcripts. Moreover, a She2p mutant defective in RNA binding still associates with RNA pol II transcribed genes. This study uncovers a novel mechanism for the cotranscriptional assembly of mRNP complexes primed for localization in the cytoplasm.
Shen
Zhifa
Z
Département de Biochimie, Université de Montréal Montréal, Quebec H3C 3J7 Canada.
St-Denis
Anik
A
Chartrand
Pascal
P
D047369:Chromatin Immunoprecipitation; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D034443:RNA Transport; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D035602:Transcriptional Elongation Factors / Q000235:genetics / Q000378:metabolism*
C098733:ASH1 protein, S cerevisiae; D002868:Chromosomal Proteins, Non-Histone; C477782:IST2 protein, S cerevisiae; D009687:Nuclear Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; C471175:SHE2 protein, S cerevisiae; C080991:SPT4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D035602:Transcriptional Elongation Factors; C069940:SPT5 transcriptional elongation factor