Solution structure of conserved AGNN tetraloops: insights into Rnt1p RNA processing.
Rnt1p, the yeast orthologue of RNase III, cleaves rRNAs, snRNAs and snoRNAs at a stem capped with conserved AGNN tetraloop. Here we show that 9 bp long stems ending with AGAA or AGUC tetraloops bind to Rnt1p and direct specific but sequence-independent RNA cleavage when provided with stems longer than 13 bp. The solution structures of these two tetraloops reveal a common fold for the terminal loop stabilized by non-canonical A-A or A-C pairs and extensive base stacking. The conserved nucleotides are stacked at the 5' side of the loop, exposing their Watson-Crick and Hoogsteen faces for recognition by Rnt1p. These results indicate that yeast RNase III recognizes the fold of a conserved single-stranded tetraloop to direct specific dsRNA cleavage.
Lebars
I
I
Laboratoire de RMN, ICSN-CNRS, 1 ave de la terrasse, F-91190 Gif-sur-Yvette, France.
Lamontagne
B
B
Yoshizawa
S
S
Aboul-Elela
S
S
Fourmy
D
D
D001483:Base Sequence; D004722:Endoribonucleases / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D043244:Ribonuclease III; D012996:Solutions
D012996:Solutions; D012313:RNA; D004722:Endoribonucleases; D043244:Ribonuclease III