Download MendeleyGene silencing activity of siRNAs with a ribo-difluorotoluyl nucleotide.
Xia, J., Noronha, A., Toudjarska, I., Li, F., Akinc, A., Braich, R., Frank-Kamenetsky, M., Rajeev, K.G., Egli, M., Manoharan, M.(2006) ACS Chem Biol 1: 176-183
- PubMed: 17163665
- DOI: https://doi.org/10.1021/cb600063p
- Primary Citation of Related Structures:
2G92 - PubMed Abstract:
Recently, chemically synthesized short interfering RNA (siRNA) duplexes have been used with success for gene silencing. Chemical modification is desired for therapeutic applications to improve biostability and pharmacokinetic properties; chemical modification may also provide insight into the mechanism of silencing. siRNA duplexes containing the 2,4-difluorotoluyl ribonucleoside (rF) were synthesized to evaluate the effect of noncanonical nucleoside mimetics on RNA interference. 5'-Modification of the guide strand with rF did not alter silencing relative to unmodified control. Internal uridine to rF substitutions were well-tolerated. Thermal melting analysis showed that the base pair between rF and adenosine (A) was destabilizing relative to a uridine-adenosine pair, although it was slightly less destabilizing than other mismatches. The crystal structure of a duplex containing rFoA pairs showed local structural variations relative to a canonical RNA helix. As the fluorine atoms cannot act as hydrogen bond acceptors and are more hydrophobic than uridine, there was an absence of a well-ordered water structure around the rF residues in both grooves. siRNAs with the rF modification effectively silenced gene expression and offered improved nuclease resistance in serum; therefore, evaluation of this modification in therapeutic siRNAs is warranted.
Organizational Affiliation:
Alnylam Pharmaceuticals, Inc., 300 Third Street, Cambridge, Massachusetts 02142, USA.
