Fig. 1.

Architecture of McrB∆NC complex. a Domain organization of McrB and McrC. b Structure of McrB∆NC and c of an McrB∆N protomer. The bound nucleotide is shown in stick representation and the magnesium ion as a green sphere. d Architecture of McrB∆N hexamer. The buried surface area at the interfaces are mentioned. Cryo-electron microscopic densities shown as isosurface mesh at 1.5 σ for e GNP-Mg²⁺ at the AB and f GDP at the DE interface. g Interactions with the guanine base at the AB interface that establish specificity for guanine. Green dashed lines represent potential hydrogen bonds