1 research outputs found
Short Interfering RNA Guide Strand Modifiers from Computational Screening
Short interfering RNAs (siRNAs) are
promising drug candidates for
a wide range of targets including those previously considered āundruggableā.
However, properties associated with the native RNA structure limit
drug development, and chemical modifications are necessary. Here we
describe the structure-guided discovery of functional modifications
for the guide strand 5ā²-end using computational screening with
the high-resolution structure of human Ago2, the key nuclease on the
RNA interference pathway. Our results indicate the guide strand 5ā²-end
nucleotide need not engage in WatsonāCrick (W/C) H-bonding
but must fit the general shape of the 5ā²-end binding site in
MID/PIWI domains of hAgo2 for efficient knockdown. 1,2,3-Triazol-4-yl
bases formed from the CuAAC reaction of azides and 1-ethynylribose,
which is readily incorporated into RNA via the phosphoramidite, perform
well at the guide strand 5ā²-end. In contrast, purine derivatives
with modified Hoogsteen faces or N2 substituents are poor choices
for 5ā²-end modifications. Finally, we identified a 1,2,3-triazol-4-yl
base incapable of W/C H-bonding that performs well at guide strand
position 12, where base pairing to target was expected to be important.
This work expands the repertoire of functional nucleotide analogues
for siRNAs