The T body, a new cytoplasmic RNA granule in Saccharomyces cerevisiae.
A large share of mRNA processing and packaging events occurs cotranscriptionally. To explore the hypothesis that transcription defects may affect mRNA fate, we analyzed poly(A)(+) RNA distribution in Saccharomyces cerevisiae strains harboring mutations in Rpb1p, the largest subunit of RNA polymerase II. In certain rpb1 mutants, a poly(A)(+) RNA granule, distinct from any known structure, strongly accumulated in a confined space of the cytoplasm. RNA and protein expressed from Ty1 retrovirus-like elements colocalized with this new granule, which we have consequently named the T body. A visual screen revealed that the deletion of most genes with proposed functions in Ty1 biology unexpectedly does not alter T-body levels. In contrast, the deletion of genes encoding the Mediator transcription initiation factor subunits Srb2p and Srb5p as well as the Ty1 transcriptional regulator Spt21p greatly enhances T-body formation. Our data disclose a new cellular body putatively involved in the assembly of Ty1 particles and suggest that the cytoplasmic fate of mRNA can be affected by transcription initiation events.
Malagon
Francisco
F
Center for mRNP Biogenesis and Metabolism, Department of Molecular Biology, University of Aarhus, C.F. Møllers Allé, Building 1130, 8000 Arhus C, Denmark.
Jensen
Torben Heick
TH
D003594:Cytoplasmic Granules / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000032:analysis; D012331:RNA, Fungal / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D018626:Retroelements; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D018626:Retroelements; C086445:SPT21 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C094737:p1 protein, yeast