Retraction for Lipardi and Paterson, Identification of an RNA-dependent RNA polymerase in Drosophila involved in RNAi and transposon suppression

BIOCHEMISTRY Retraction for “Identification of an RNA-dependent RNA polymerase in Drosophila involved in RNAi and transposon suppression,” by Concetta Lipardi and Bruce M. Paterson, which appeared in issue 37, September 15, 2009, of Proc Natl Acad Sci USA (106:15645–15650; first published September 1, 2009; 10.1073/pnas.0904984106).

The authors wish to note the following: “In our article, we reported that recombinant subunit 1 of the Drosophila elongator complex, D-elp1, had RNA-dependent RNA polymerase (RdRP) activity and was involved in RNAi, transposon suppression, and endo-siRNA production, but not miRNA targeting. RdRP activity was identified using three assays to interrogate the reaction products: Dcr2 digestion, RNase sensitivity, and nearest neighbor analysis. Although we do see differential Dcr2 cleavage and RNase resistance, the gold standard for second strand RNA synthesis is nearest neighbor analysis, as described previously for the Neurospora crassa RdRP, QDE-1 (1). Subsequent studies revealed that the nearest neighbor analysis was misinterpreted because of two factors unknown to us at the time: First, T7 run-off transcripts used as single-stranded RNA templates have heterogeneous 3' termini (2, 3); Second, the Flag-tag affinity purified recombinant D-elp1 protein preparations used in our study contain a ribonucleotide terminal transferase activity able to catalyze the addition of single a-labeled ribonucleotide triphosphates to the 3' hydroxyl terminus of the template RNA. Therefore, nearest neighbor analysis measured the heterogeneous 3' termini of the template RNA and not second strand RNA synthesis, as initially reported. Given this result, we wish to rescind the interpretation that D-elp1 can be considered as an RNA-dependent RNA polymerase. The basis for the ribonucleotide terminal transferase activity is under investigation. The interpretation of the results does not detract from the fact that D-elp1 is involved in RNAi, endo-siRNA production, and transposon suppression, but not miRNA targeting as shown in Figs. 3 and 4. By clarifying this issue, we hope to promote further productive investigation into the role of elongator subunit 1 in RNAi and transposon suppression. We apologize for any difficulties our original interpretation may have caused other investigators and hereby retract the paper.”

Concetta Lipardi

Bruce M. Paterson