Poster abstracts

Poster number 79 submitted by Heather Woolls

Shining the Light on Dim2

Heather Woolls (Chemical Biology Doctoral Program), Katrin Karbstsein (Chemistry Department, Chemical Biology Doctoral Program)

Abstract:
Ribosomes catalyze protein synthesis in all cells and as such are among the most important biomolecules. In eukaryotes assembly of ribosomes requires >200 RNA and protein cofactors, whose function remains poorly understood. In S. cerevisiae, the final cytoplasmic step in the maturation of the 40S (small) subunit involves cleavage of the 20S rRNA precursor to the final 18S product. Several accessory factors are involved in this step including two proteins Nob1 and Dim2 (1,2). While Nob1 is the endonuclease responsible for cleavage of the 20S rRNA (1, 3, 4) the function of Dim2 remains unknown. Previous research suggested an interaction between Nob1 and Dim2 (5). Sequence alignments suggest that Dim2 contains three putative KH domains. Various truncations of full length Dim2, including deletion of the N-terminal and C-terminal regions, were cloned and purified. As shown previously (6), our data implicate the C-terminal KH domain in rRNA binding. Preliminary analysis by size exclusion chromotagraphy shows that the N-terminal region is responsible for dimerization of Dim2. Initial pull-down data indicate that the middle domain of Dim2 is likely responsible for binding Nob1. A model of Dim2 suggests W113 and K115 as candidates for residues involved in the interaction with Nob1. We are currently testing the role of these residues in protein-protein binding. Once the Dim2-Nob1 interaction has been detailed in vitro, we will determine the effect of this interaction on ribosome assembly in vivo.

References:
1. Fatica, A., Oeffinger, M., Dlakic, M., and Tollervey, D. Mol and Cell Biol. 2003; 23: 1798.
2. Senapin, S, Clark-Walker, G. D., Chen, X. J., Serapin, B., and Daugeron, M. Nucleic Acids Res. 2003; 31: 2524.
3. Fatica, A., Tollervey, D., and Dlakic, M. RNA. 2004; 10: 1698.
4. Lamanna, A. and Karbstein, K. PNAS. (2009) submitted for publication.
5. Tone, Y., and Toh-e, A. Genes Dev. 2002; 16: 3142.
6. Vanrobays, E., Leplus, A., Osheim, Y. N., Beyer, A., Wacheul, L., and Lafontaine, D. RNA. 2008; 14: 2061.

Keywords: Ribosome Assembly, Dim2, KH domain