FIG 3.
l-Methionine binding to MetQ. (A) (i and ii) SPR sensograms (i) and line-of-best-fit curve (ii) of l-methionine binding to immobilized recombinant MetQ protein. The line of best fit was generated in Biacore T100 Evaluation software, with χ2 values for all experiments falling under 0.1 of the maximum response units (Rmax). Single-cycle kinetics were used to generate the KD of the interactions between MetQ and the l-methionine substrate. (iii) SPR sensograms showing no interaction between the negative control (alanine) and immobilized MetQ. (B) ITC of the interaction of the N. gonorrhoeae 1291 wild-type (i), metQ knockout (ΔmetQ) (ii), and complemented (C-metQ) (iii) strains with l-methionine. The graphs show heat changes upon injection of l-methionine, which is dependent on the presence of MetQ.