SUNY at Albany
June 19-23, 2001
Solution structure of a conserved RNA tetraloop: the recognition site of Saccharomyces cerevisiae RNase III
Yeast RNase III (Rnt1p), a double-stranded RNA (dsRNA) endonuclease, is required for processing of a large number of RNA precursors. Studies have shown that all substrates of Rnt1p have a structure in which a double-stranded RNA is capped by a consensus AGNN tetraloop located within 13-16 bp from the Rnt1p cleavage sites. These tetraloops have been shown to be essential for Rnt1p cleavage, and the distance to the tetraloop is the primary determinant of cleavage site selection (G. Chanfreau, A. Jacquier, 2000).
We will present the solution structures of two RNA hairpins capped by AGNN tetraloops, AGAA and AGUU, determined by NMR spectroscopy. The tetraloops display an unexpected structure similar to the UGAA tetraloop. The backbone turn occurs between the G and the third residue in the loop, with the first A and G in a 5' stack and the other two residues in a 3' stack. The correlation between the activity of Rnt1p on different tetraloop sequences and their structures will be discussed.Reference and Footnotes
Haihong Wu*, Samuel E. Butcher, Sundeep Kang and Juli Feigon
Department of Chemistry and Biochemistry, P.O. Box 951569, University of California, Los Angeles, CA 90095-1569, USA