Eukaryotic Ribosome Biogenesis
Ribosomes are supramolecular assembly of RNA and proteins, responsible for translating the genetic information. Ribosome consists of two unequal subunits (40S and 60S). The small subunit decodes the mRNA, whereas the large subunit catalyzes the formation of peptide bonds. The eukaryotic ribosome biogenesis is a complex multistep process where approximately 80 ribosomal proteins and 4 rRNAs are assembled into mature ribosomal particles (Kressler et al., 1999). More than 200 additional proteins and snoRNAs are needed for the biosynthesis of a eukaryotic ribosome.
The basic process of ribosome biogenesis is conserved within eukaryotes, but the most detailed results have been obtained with S.cerevisiae as the model system owing to its excellent genetic and biochemical suitability.
My lab´s primary interest is to understand the processing and assembly of ribosomal subunits. The four mature rRNAs that form the ribosome are transcribed from a rDNA which is organized as a tandem array by two distinct RNA polymerases with RNA polymerase I synthesizing the larger 35S rRNA precursor and RNA polymerase III synthesizing the smaller pre-5S rRNA (Fatica and Tollervey, 2002). After being transcribed in the nucleolus the nascent 35S pre-rRNA assembles with the machineries that catalyze the successive steps in rRNA processing, modification and folding as well as assembly of ribosomal proteins into a 90S particle.The 35S pre-rRNA is chemically modified and cleaved at three positions, A0, A1, and A2, to generate the intermediate 33S, 32S, 27SA2, 20S RNA precursors which then follow to independent routes through 20S and 27SA2 to the generation of either the 18S rRNA or 5.8S and 25S rRNA which are the components of 40S and 60S ribosomal subunits, respectively (Dragon et al., 2002).
During the processing of the 35S rDNA, it is also chemically decorated with various modifications like 2´O ribose methylation, base methylation and pseudouridylation. Our group is presently working on the identification and significance of such modifications in the 25S rRNA of Saccharomyces cerevisiae
- Anatoli Lioutikov (Graduate Student)
- Britta Meyer (Post Doc.)
- Jun Yang (Graduate student)
- Peter Watzinger (Technical Assistant)
- Stefanie Lamberth (Technical Assistant)
- Sunny Sharma (Graduate Student)