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. 2010 Dec 30;108(3):903–910. doi: 10.1073/pnas.1017762108

Fig. 2.

Fig. 2.

Crystal structure of the Hiwi1 PAZ-RNA complex. (A) Ribbon representation of the structure of the Hiwi1 PAZ-RNA complex. The RNA is a self-complementary 14-mer (12-bp + 2-nt overhang) sequence containing 2′-OCH3 at its 3′ end. The complex contains Hiwi1 PAZ modules bound to the 2-nt overhangs at either end of the RNA duplex. (B) Experimental electron density (Fo - Fc map) observed for the methyl group of 2′-OCH3 of Um in the Hiwi1-PAZ-RNA complex. Fo - Fc map is contoured at 2.0σ and shown in magenta. Electron density (2Fo - Fc map) corresponding to terminal nucleotide Um without methyl group (green) is contoured at 1.8σ and shown in black. (C) Stereo view of the structure of the Hiwi1 PAZ-RNA complex containing one PAZ domain bound to the overhang-containing strand, corresponding to the 1∶1 PAZ∶ssRNA stoichiometry seen in the asymmetric unit in the crystal. (D) Stereo view of intermolecular interactions between 2-nt U13-Um14 overhang (in green) with labeled amino acid side chains (in biscuit) lining the Hiwi1 PAZ-binding pocket. Intermolecular hydrogen-bonds are indicated by dashed silver lines.