Figure 5.

Disruption of DPN–triloop interaction in the crystal structures of N128 mutants. (A–C) The crystal structures of WT (green), N128A (blue), and N128D (yellow) indicated how the mutation affected the hydrogen bonding network and D-loop. The hydrogen bonds are shown by blue dotted lines. (A) The crystal structure of WT was co-crystallized with vanadate, and the DPN–triloop interaction was maintained. (B) N128 was replaced with alanine, and the conformation of the D-loop changed. Only one hydrogen bond was formed between the side chain of S93 and backbone amide of N128. (C) N128 was replaced with a somatic mutant, aspartate. The D128 induced charge repulsion with D57 and resulted in a dynamic D-loop that had unclear electron density.