Poster abstracts

Poster number 33 submitted by Allison Lamanna

Investigating interactions of the putative endonuclease Nob1 with 18S rRNA

Allison C. Lamanna (Chemistry Department, University of Michigan), Katrin Karbstein (Chemistry Department, University of Michigan)

Abstract:
Nob1 is an essential Saccharomyces cerevisiae protein involved in ribosome biogenesis. Specifically, cells depleted in Nob1 show a defect in processing of the 40S small ribosomal subunit rRNA: cleavage of 20S to form the mature 3’ end of 18S rRNA does not occur (1). Because Nob1 contains a predicted PIN domain that is required for this cleavage (2), it has been proposed that Nob1 is the endonuclease responsible for maturation of the 20S rRNA to 18S rRNA. Here, we show that Nob1 binds to rRNA fragments from the 3’ end of the 20S rRNA. Additionally, while Nob1 is a monomer in solution, it oligomerizes on the rRNA substrate. Homology modeling of the Nob1 PIN domain has suggested that Nob1 can form a tetramer through interactions in this domain (2). Further work will explore the ability of Nob1 to cleave 20S rRNA fragments and the stoichiometry of the Nob1-rRNA interaction.

References:
(1) Fatica, A., Oeffinger, M., Dlakic, M., and Tollervey, D. (2003) Mol. Cell. Biol. 23, 1798-1807.
(2) Fatica, A., Tollervey, D., and Dlakic, M. (2004) RNA 10, 1698-1701.

Keywords: endonuclease, ribosome biogensis, Saccharomyces cerevisiae