Structural basis for gene silencing by siRNAs in humans.

ABSTRACT: Small interfering RNAs (siRNAs) guide mRNA cleavage by human Argonaute2 (hAgo2), leading to targeted gene silencing. Despite their laboratory and clinical impact, structural insights into human siRNA catalytic activity remain elusive. Here, we show that disrupting siRNA 3'-end binding by hAgo2 accelerates target cleavage and stabilizes its catalytic conformation, enabling detailed structural analysis. A 3.16 Å global resolution cryo-EM reconstruction reveals that distortion of the siRNA-target duplex at position 6 allows target RNA entry into the catalytic cleft and shifts Lysine-709, a previously unrecognized catalytic residue, into the active site. A pyrimidine at target nucleotide t10 positions another unrecognized catalytic residue, Arginine-710, for optimal cleavage. Expansion of the

SUBMITTER: Sarkar S 

PROVIDER: S-EPMC11643337 | biostudies-literature | 2024 Dec

REPOSITORIES: biostudies-literature