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. Author manuscript; available in PMC: 2023 Nov 3.
Published in final edited form as: Mol Cell. 2022 Sep 30;82(21):4049–4063.e6. doi: 10.1016/j.molcel.2022.09.002

Figure 6. Conformational transitions define ordered product release.

Figure 6.

(A) Overall views of the pre-miRNA-bound Dcr-1•Loqs-PB complex in presence of Mg2+ before cleavage (structure IIb), after cleavage of the 5′ arm of the model pre-miRNA (structure III) and after cleavage of both the 5′ and 3′ arms (structure IV).

(B) Close-up view showing differences in the positions of the Dcr-1 dsRBD and Hel2i domains and the Loqs-PB dsRBD-3 in the Dcr-1•Loqs-PB•pre-miRNA structure IV after both 5′ and 3′ arms of the pre-miRNA have been cleaved (red and blue) relative to those in structure III after cleavage of the 5′ arm of the model pre-miRNA (protein domains in dark gray). Structural alignments were performed by superposition of Dcr-1•Loqs-PB•pre-miRNA complexes. Black arrows indicate conformational changes upon the second cleavage event.

(C) Structure of Dcr-1•Loqs-PB•pre-miRNA complex in surface (protein) and cartoon (RNA) views, showing the mature miRNA/miRNA* duplex remaining anchored to the Dcr-1 PAZ and platform domains.

(D) Superposition of atomic models of mature duplex (structure IV) and pre-miRNA (structure IIb), showing the lower part of the duplex (red and blue) shifted ~5 Å from its position before cleavage (gray). RNA shown in cartoon representation. RNase IIIa catalytic center (structure IV) shown as sticks.