Fig. 4: Model of cA6-mediated allosteric activation mechanism of Csm6 RNases. | Nature Communications

Fig. 4: Model of cA6-mediated allosteric activation mechanism of Csm6 RNases.

From: Activation and self-inactivation mechanisms of the cyclic oligoadenylate-dependent CRISPR ribonuclease Csm6

Fig. 4

a Zoom-in view of the HEPN domain ribonuclease active site in EiCsm6. The conserved R372, N373, H377 residues of the HEPN catalytic motif, and additionally R274, are represented as sticks. Electron density, interpreted as a sulfate ion (depicted as 2mFO–DFC composite omit map, contoured at 1.0 σ and displayed within a radius of 2.2 Å), is located within hydrogen bonding distance of H377, likely mimicking the scissile phosphate group of an RNA substrate. b Schematic model of the cA6-mediated allosteric activation mechanism of Csm6 enzymes.

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