Length distribution of cleavage products is affected by the rate of product release. (A) On the left: cartoon illustration of the crystal structure of the AaRNase III dimer in complex with dsRNA (PDB entry 2EZ6); on the right: zoom-in window shows relative positioning of side chains E37, E64 and Q161, of which the counterparts in EcRNase III are E38, E65 and Q165, respectively. (B–G) FF-luc and MBP dsRNAs were cleaved by various RNase III mutants. The length of products was compared to that of the wild-type. Fold changes in log scale are plotted against product lengths for EcE38A (B), EcE65A (C), EcQ165A (D), AaE37A (E), AaE64A (F) and AaQ161A (G).