Contributions of Trf4p- and Trf5p-dependent polyadenylation to the processing and degradative functions of the yeast nuclear exosome.
The nuclear exosome is involved in a large number of RNA processing and surveillance pathways. RNase III cleavage intermediates destined to be 3'-processed or degraded can be detected when the Rrp6p subunit of the nuclear exosome is absent. Here we show that these processing and degradation intermediates are polyadenylated, and that their polyadenylation is dependent on the activity of Trf4p and Trf5p, two variant poly(A) polymerases. Polyadenylation of cleavage intermediates was inhibited when Trf4p was absent, and reduced to various extents in the absence of Trf5p, suggesting that these two poly(A) polymerases play functionally distinct roles in the polyadenylation of these RNA species. Finally, in the absence of Trf4p, we observed 3'-extended forms of the U4 snRNA that are similar to those observed in the absence of Rrp6p. These results suggest that polyadenylation of RNA processing intermediates plays a functional role in RNA processing pathways and is not limited to RNA surveillance functions.
Egecioglu
Defne E
DE
Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California Los Angeles, Box 951569, Los Angeles, CA 90095-1569, USA.
Henras
Anthony K
AK
Chanfreau
Guillaume F
GF
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D005092:Exonucleases / Q000378:metabolism*; D026723:Polyadenylation; D026721:RNA 3' End Processing; D012333:RNA, Messenger / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000378:metabolism; D020537:RNA, Small Nucleolar / Q000378:metabolism; D043244:Ribonuclease III / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
D012333:RNA, Messenger; D012342:RNA, Small Nuclear; D020537:RNA, Small Nucleolar; D029701:Saccharomyces cerevisiae Proteins; D012321:DNA-Directed RNA Polymerases; C506067:Trf5 protein, S cerevisiae; D004259:DNA-Directed DNA Polymerase; C487545:PAP2 protein, S cerevisiae; D005092:Exonucleases; C468367:RNT1 protein, S cerevisiae; D043244:Ribonuclease III