General, rapid, and transcription-dependent fragmentation of nucleolar antigens in S. cerevisiae mRNA export mutants.
In the yeast Saccharomyces cerevisiae, mutation of some effectors of mRNA nuclear export leads to the rapid accumulation of HSP104 RNA in transcription site-associated foci. We have screened the S. cerevisiae complement of viable gene deletion mutants for their inability to export HSP104 RNA. The 15 strains identified comprise deletions of components of the THO, Thp1p/Sac3p, and nuclear pore complexes. In all three mutant classes, retained RNA overlaps the HSP104 transcription site. Thus, an early block to HSP104 RNA export is general. Incubation of the identified deletion strains, as well as seven additional mutants, under conditions where mRNA export is blocked results in rapid dissipation of nucleolar protein and RNA constituents. Time course experiments show that dissipation of nucleolar antigens succeeds mRNA retention and is reversed when the load of nuclear mRNA ceases. Consistent with a causal role of excess nuclear mRNA, nucleolar morphology in an mRNA export mutant environment remains intact when transcription by RNA polymerase II is inhibited.
Thomsen
Rune
R
Centre for mRNP Biogenesis and Metabolism, Department of Molecular Biology, University of Aarhus, DK-8000 Aarhus C, Denmark.
Saguez
Cyril
C
Nasser
Tommy
T
Jensen
Torben Heick
TH
D021581:Active Transport, Cell Nucleus; D000946:Antigens, Fungal / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002466:Cell Nucleolus / Q000378:metabolism; D017353:Gene Deletion; D005800:Genes, Fungal; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D015345:Oligonucleotide Probes / Q000235:genetics; D012319:RNA Polymerase II / Q000378:metabolism; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D000946:Antigens, Fungal; D006360:Heat-Shock Proteins; D009687:Nuclear Proteins; D015345:Oligonucleotide Probes; D012331:RNA, Fungal; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; C070972:HsP104 protein, S cerevisiae; D012319:RNA Polymerase II