FIGURE 5.

Apparent DSMP K_m perturbations of lipid-binding pocket alanine mutants mapped onto the LpxK-lipid IV_A coordinates. In order to visualize the effects of alanine mutants of conserved residues within the lipid-binding pocket on the apparent DSMP K_m, these residues are shaded in the model based on how much this parameter is increased when mutated to alanine using the following criteria: 0–4-fold K_m increase, white; 4–8-fold K_m increase, gray; >8-fold K_m increase, black. With the exception of Arg¹¹⁹, the alanine mutants of residues that appear to contact the lipid increase the K_m at least 4-fold. Arg¹⁷¹ appears to be the most critical residue for lipid substrate binding, with an increased DSMP K_m 20-fold higher than wild type. Potential hydrogen bonding interactions are shown as magenta dashes. Font size is indicative of depth.