Publication Date:
2004-11-20
Description:
To act as guides in the RNA interference (RNAi) pathway, small interfering RNAs (siRNAs) must be unwound into their component strands, then assembled with proteins to form the RNA-induced silencing complex (RISC), which catalyzes target messenger RNA cleavage. Thermodynamic differences in the base-pairing stabilities of the 5' ends of the two approximately 21-nucleotide siRNA strands determine which siRNA strand is assembled into the RISC. We show that in Drosophila, the orientation of the Dicer-2/R2D2 protein heterodimer on the siRNA duplex determines which siRNA strand associates with the core RISC protein Argonaute 2. R2D2 binds the siRNA end with the greatest double-stranded character, thereby orienting the heterodimer on the siRNA duplex. Strong R2D2 binding requires a 5'-phosphate on the siRNA strand that is excluded from the RISC. Thus, R2D2 is both a protein sensor for siRNA thermodynamic asymmetry and a licensing factor for entry of authentic siRNAs into the RNAi pathway.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tomari, Yukihide -- Matranga, Christian -- Haley, Benjamin -- Martinez, Natalia -- Zamore, Phillip D -- GM62862-01/GM/NIGMS NIH HHS/ -- GM65236-01/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2004 Nov 19;306(5700):1377-80.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15550672" target="_blank"〉PubMed〈/a〉
Keywords:
Animals
;
Argonaute Proteins
;
Dimerization
;
Drosophila/embryology/metabolism
;
Drosophila Proteins/*metabolism
;
Light
;
Luciferases/genetics
;
Nucleic Acid Conformation
;
RNA Helicases/*metabolism
;
*RNA Interference
;
RNA, Double-Stranded/chemistry/metabolism
;
RNA, Small Interfering/*chemistry/*metabolism
;
RNA-Binding Proteins/*metabolism
;
RNA-Induced Silencing Complex/*metabolism
;
Ribonuclease III
;
Superoxide Dismutase/genetics
;
Thermodynamics
;
Uracil/*analogs & derivatives/analysis
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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