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. Author manuscript; available in PMC: 2013 Sep 5.
Published in final edited form as: Structure. 2012 Jul 26;20(9):1574–1584. doi: 10.1016/j.str.2012.06.016

Figure 3. Crystal structure of Csd5d.

Figure 3

(A) Cas5d consists of an N-terminal ferredoxin domain (β1- β6; cyan) with an additional β-sheet insertion (β3-β4; yellow). This insertion and a C-terminal twisted β-sheet (β7-β10; pink) form a “wall” fencing the ferredoxin domain (see the side view to the right). An unstructured C-terminal tail interacts with the ferredoxin fold of an adjacent molecule. (B) Surface representation of Cas5d highlighting the putative pre-crRNA binding pocket (in yellow). The “walls” by the β-sheet insertions were colored in gold, and the catalytic triad in red. (C) Top: purity of the Cas5d deletion mutants after purification. Bottom: Deletion mapping showing that the twisted β-sheet is required for the pre-crRNA cleavage activity of Cas5d, whereas the C-terminal tail is not. 0.2 μM of proteins and 0.2 μM of 5′-Hex labeled pre-crRNA were incubated with Cas5d proteins for 20 min at 25°C. See also Figure S2.