A block to mRNA nuclear export in S. cerevisiae leads to hyperadenylation of transcripts that accumulate at the site of transcription.
Several factors contribute to nuclear mRNA export in Saccharomyces cerevisiae, including Mex67p, Mtr2p, Gle1p, Nup159p, Dbp5p, and Rip1p. Strains carrying mutations in these factors show rapid and dramatic nuclear accumulation of poly(A)(+) RNA. We have characterized two heat shock mRNAs, SSA4 and HSP104, in these mutant backgrounds; each transcript concentrates in a single intranuclear focus. Evidence suggests that it coincides with the site of transcription. Interestingly, all detectable SSA4 transcripts have undergone 3'-end formation, indicating that RNAs in the foci are no longer nascent. Poly(A) tails of the transcripts are also dramatically longer in all of these export mutants. Based on all of the data, we suggest that very early mRNA maturation events determine transcript export competence.
Jensen
T H
TH
Howard Hughes Medical Institute, Department of Biology, Brandeis University, Waltham, MA 02454, USA.
Patricio
K
K
McCarthy
T
T
Rosbash
M
M
D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D020690:GTPase-Activating Proteins / Q000235:genetics; D005690:Galactose / Q000494:pharmacology; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D018869:Heat-Shock Response / Q000235:genetics; D006358:Hot Temperature; D012331:RNA, Fungal / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic / Q000502:physiology*
D020690:GTPase-Activating Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; C070972:HsP104 protein, S cerevisiae; D005690:Galactose