Poster abstracts

Poster number 87 submitted by Chandani Warnasooriya

Single molecule studies of Prp24-dependent folding dynamics of the U2/U6 complex

Chandani Warnasooriya (Department of Chemistry, Wayne state University, Detroit, MI 48202), Zhuojun Guo (Department of Chemistry, Wayne state University, Detroit, MI 48202), David Rueda (Department of Chemistry, Wayne state University, Detroit, MI 48202)

Abstract:
Splicing is catalyzed by the spliceosome, which consists of five small nuclear ribonucleoprotein particles (snRNPs): U1, U2, U4, U5 and U6 and associates with several protein factors that facilitate structural rearrangements in the spliceosome [1, 2]. Proper assembly of spliceosomal components is critical for function, and thus, defects in assembly can be lethal [3, 4]. In our lab, we use Fluorescence Resonance Energy Transfer (FRET) along with single molecule detection to study the structural dynamics of the snRNA complexes and the effect of protein factors on those complexes. Our previous studies have shown that the U2/U6 complex undergoes conformational changes and has at least three conformations with three distinct FRET values [5]. Here we study the effect of Prp24, an snRNP protein, on the structural dynamics of U2/U6 complex. Our single molecule data reveals that binding of Prp24 affects the conformational dynamics of U2/U6 complex and it stabilizes the low FRET conformation. With these results we propose that Prp24 plays a major role in spliceosomal assembly and function; more specifically binding of Prp24 toggles U6 between active and inactive conformations such that it is only catalytically active when all components at activated spliceosome are present and are ready for splicing.

References:
1.Wahl, M.C., C.L. Will, and R. Luhrmann, The spliceosome: design principles of a dynamic RNP machine. Cell, 2009. 136(4): p. 701-18.
2.Will, C.L. and R. Luhrmann, Spliceosome structure and function. Cold Spring Harb Perspect Biol, 2011. 3(7).
3.Cooper, T.A., L. Wan, and G. Dreyfuss, RNA and disease. Cell, 2009. 136(4): p. 777-93.
4.Wang, G.S. and T.A. Cooper, Splicing in disease: disruption of the splicing code and the decoding machinery. Nat Rev Genet, 2007. 8(10): p. 749-61.
5.Guo, Z., K.S. Karunatilaka, and D. Rueda, Single-molecule analysis of protein-free U2-U6 snRNAs. Nat Struct Mol Biol, 2009. 16(11): p. 1154-9.

Keywords: Prp24, spliceosome, single molecule