Ancestral Roles of Small RNAs: An Ago-Centric Perspective
Leemor Joshua-Tor and Gregory J. Hannon
-Author Affiliations
Watson School of Biological Sciences, Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724
Correspondence: hannon@cshl.edu and leemor@cshl.edu
SUMMARY
RNAi has existed at least since the divergence of prokaryotes and eukaryotes. This collection of pathways responds to a diversity of “abberant” RNAs and generally silences or eliminates genes sharing sequence content with the silencing trigger. In the canonical pathway, double-stranded RNAs are processed into small RNAs, which guide effector complexes to their targets by complementary base pairing. Many alternative routes from silencing trigger to small RNA are continuously being uncovered. Though the triggers of the pathway and the mechanisms of small RNA production are many, all RNAi-related mechanisms share Argonaute proteins as the heart of their effector complexes. These can act as self-contained silencing machines, binding directly to small RNAs, carrying out homology-based target recognition, and in some cases cleaving targets using an endogenous nuclease domain. Here, we discuss the diversity of Argonaute proteins from a structural and functional perspective.
Copyright © 2010 Cold Spring Harbor Laboratory Press; all rights reserved
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