TY - JOUR
T1 - A Two-Hit Trigger for siRNA Biogenesis in Plants
AU - Axtell, Michael J.
AU - Jan, Calvin
AU - Rajagopalan, Ramya
AU - Bartel, David P.
N1 - Funding Information:
We thank the Joint Genome Institute for the availability of P. patens WGS traces, Mitsuyasu Hasebe for the gift of P. patens spores and protocols, Herve Vaucheret for sharing the tas3-1 homozygous line and pART27-AtTAS3 construct prior to publication, Wendy Johnston for technical assistance, Guiliang Tang for advice on wheat-germ assays, and Matt Jones-Rhoades for computational assistance. This work was supported by a grant from the NIH, the Prix Louis D. from the Institut de France (D.P.B.), a Helen Hay Whitney Postdoctoral Fellowship (M.J.A.), and an NSF predoctoral fellowship (C.J.).
PY - 2006/11/3
Y1 - 2006/11/3
N2 - In Arabidopsis, microRNA-directed cleavage can define one end of RNAs that then generate phased siRNAs. However, most miRNA-targeted RNAs do not spawn siRNAs, suggesting the existence of additional determinants within those that do. We find that in moss, phased siRNAs arise from regions flanked by dual miR390 cleavage sites. AtTAS3, an siRNA locus important for development and conserved among higher plants, also has dual miR390 complementary sites. Both sites bind miR390 in vitro and are functionally required in Arabidopsis, but cleavage is undetectable at the 5′ site-demonstrating that noncleavable sites can be functional in plants. Phased siRNAs also emanate from the bounded regions of every Arabidopsis gene with two known microRNA/siRNA complementary sites, but only rarely from genes with single sites. Therefore, two "hits,"-often, but not always, two cleavage events-constitute a conserved trigger for siRNA biogenesis, a finding with implications for recognition and silencing of aberrant RNA.
AB - In Arabidopsis, microRNA-directed cleavage can define one end of RNAs that then generate phased siRNAs. However, most miRNA-targeted RNAs do not spawn siRNAs, suggesting the existence of additional determinants within those that do. We find that in moss, phased siRNAs arise from regions flanked by dual miR390 cleavage sites. AtTAS3, an siRNA locus important for development and conserved among higher plants, also has dual miR390 complementary sites. Both sites bind miR390 in vitro and are functionally required in Arabidopsis, but cleavage is undetectable at the 5′ site-demonstrating that noncleavable sites can be functional in plants. Phased siRNAs also emanate from the bounded regions of every Arabidopsis gene with two known microRNA/siRNA complementary sites, but only rarely from genes with single sites. Therefore, two "hits,"-often, but not always, two cleavage events-constitute a conserved trigger for siRNA biogenesis, a finding with implications for recognition and silencing of aberrant RNA.
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U2 - 10.1016/j.cell.2006.09.032
DO - 10.1016/j.cell.2006.09.032
M3 - Article
C2 - 17081978
AN - SCOPUS:33750440526
SN - 0092-8674
VL - 127
SP - 565
EP - 577
JO - Cell
JF - Cell
IS - 3
ER -