Phosphate and R2D2 Restrict the Substrate Specificity of Dicer-2, an ATP-Driven Ribonuclease

UMMS Affiliation

Department of Biochemistry and Molecular Pharmacology



Document Type


Medical Subject Headings

Drosophila Proteins; RNA Helicases; Ribonuclease III; RNA, Small Interfering; MicroRNAs; RNA, Double-Stranded; Adenosine Triphosphate; Substrate Specificity


Drosophila Dicer-2 generates small interfering RNAs (siRNAs) from long double-stranded RNA (dsRNA), whereas Dicer-1 produces microRNAs (miRNAs) from pre-miRNA. What makes the two Dicers specific for their biological substrates? We find that purified Dicer-2 can efficiently cleave pre-miRNA, but that inorganic phosphate and the Dicer-2 partner protein R2D2 inhibit pre-miRNA cleavage. Dicer-2 contains C-terminal RNase III domains that mediate RNA cleavage and an N-terminal helicase motif, whose function is unclear. We show that Dicer-2 is a dsRNA-stimulated ATPase that hydrolyzes ATP to ADP; ATP hydrolysis is required for Dicer-2 to process long dsRNA, but not pre-miRNA. Wild-type Dicer-2, but not a mutant defective in ATP hydrolysis, can generate siRNAs faster than it can dissociate from a long dsRNA substrate. We propose that the Dicer-2 helicase domain uses ATP to generate many siRNAs from a single molecule of dsRNA before dissociating from its substrate.

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Citation: Cenik et al., Phosphate and R2D2 Restrict the Substrate Specificity of Dicer-2, an ATP-Driven Ribonuclease, Molecular Cell (2011), doi:10.1016/j.molcel.2011.03.002


Co-author Elif Sarinay Cenik is a student in the Biochemistry & Molecular Pharmacology program in the Graduate School of Biomedical Sciences (GSBS) at UMass Medical School.

Related Resources

Link to article in PubMed


Dicer-1, Dicer-2, R2D2, ATP, helicase, phosphate, processivity, substrate specificity

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