Synthesis of functional eukaryotic ribosomal RNAs in trans: Development of a novel in vivo rDNA system for dissecting ribosome biogenesis

Synthesis of functional eukaryotic ribosomal RNAs in trans: Development of a novel in vivo rDNA system for dissecting ribosome biogenesis

Department of Biochemistry and Molecular Biology and The Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003

Abstract

Active 18S and 25S ribosomal RNAs were produced in trans in yeast, from plasmids containing RNA polymerase II transcription signals and rDNA fragments with unique hybridization tags. Analyses were carried out in cells with temperature-sensitive RNA polymerase I. Functional rRNAs were derived from separate 18S and 5.8/25S rRNA coding units, however, active 25S rRNA could be produced only by cotranscription with 5.8S rRNA. The results demonstrate that the polycistronic organization of the large rDNA operon is not required for successful processing of rRNA or assembly of functional ribosomes. The split operon system should facilitate future efforts to dissect eukaryotic ribosome biogenesis.

Footnotes

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Masayasu Nomura, University of California, Irvine, CA
ABBREVIATIONS:

5′ ETS,

5′ external transcribed spacer;

snoRNA,

small nucleolar RNA;

ITS1,

internal transcribed spacer-one sequence;

ITS2,

second internal transcribed spacer