Lsm proteins are required for normal processing of pre-tRNAs and their efficient association with La-homologous protein Lhp1p.
Depletion of any of the five essential proteins Lsm2p to Lsm5p and Lsm8p leads to strong accumulation of all tested unspliced pre-tRNA species, as well as accumulation of 5' and 3' unprocessed species. Aberrant 3'-extended pre-tRNAs were detected, presumably due to stabilization of transcripts that fail to undergo correct transcription termination, and the accumulation of truncated tRNA fragments was also observed. Tandem affinity purification-tagged Lsm3p was associated with pre-tRNA primary transcripts and, less efficiently, with other unspliced pre-tRNA intermediates but not mature tRNAs. Association of the Saccharomyces cerevisiae La homologue Lhp1p with pre-tRNAs was reduced approximately threefold on depletion of Lsm3p or Lsm5p. The association of Lhp1p with larger RNA polymerase III transcripts, pre-RNase P RNA and the signal recognition particle RNA (scR1), was more drastically reduced. The impaired pre-tRNA processing seen on Lsm depletion is not, however, due solely to reduced Lhp1p association as evidenced by analysis of lhp1-Delta strains depleted of Lsm3p or Lsm5p. These data are consistent with roles for an Lsm complex as a chaperone that facilitates the efficient association of pre-tRNA processing factors with their substrates.
Kufel
Joanna
J
Wellcome Trust Centre for Cell Biology, The University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK.
Allmang
Christine
C
Verdone
Loredana
L
Beggs
Jean D
JD
Tollervey
David
D
D005656:Fungal Proteins / Q000378:metabolism*; D009154:Mutation; D012322:RNA Precursors / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D016601:RNA-Binding Proteins / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
D005656:Fungal Proteins; C088396:LHP1 protein, S cerevisiae; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D017411:Ribonucleoproteins, Small Nuclear; D029701:Saccharomyces cerevisiae Proteins