Cic1p/Nsa3p is required for synthesis and nuclear export of 60S ribosomal subunits.
Cic1p/Nsa3p was previously reported to be associated with the 26S proteasome and required for the degradation of specific substrates, but was also shown to be associated with early pre-60S particles and to be localized to the nucleolus. Here we report that Cic1p/Nsa3p is required for the synthesis of 60S ribosome subunits. A temperature-sensitive lethal cic1-2 point mutation inhibits synthesis of the mature 5.8S and 25S rRNAs. Release of the pre-60S particles from the nucleolus to the nucleoplasm was also inhibited as judged by the nuclear accumulation of an Rpl11b-GFP reporter construct. We suggest that Cic1p/Nsa3p associates early with nascent preribosomal particles and is required for correct processing and nuclear release of large ribosomal subunit precursors.
Fatica
Alessandro
A
Department of Genetics and Molecular Biology, University of Rome "La Sapienza," Rome, Italy. alessandro.fatica@uniroma1.it
Oeffinger
Marlene
M
Tollervey
David
D
Bozzoni
Irene
I
D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism*; D017931:DNA Primers; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012270:Ribosomes; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*
D002352:Carrier Proteins; C437314:Cic1 protein, S cerevisiae; D017931:DNA Primers; D008164:Luminescent Proteins; D012335:RNA, Ribosomal; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins