A mosquito juvenile hormone binding protein (mJHBP) regulates the activation of innate immune defenses and hemocyte development
Fig 5
Mutagenesis and ligand binding profiling of mJHBP.
A. The JH III binding site is located in the N-terminal domain (N-term). In the wild type mJHBP-JH III complex helix α-13 of the C-terminal domain covers the ligand access channel (red). The α-13 position in the presumed open form of the ligand-free protein would be folded back over the C-terminal domain (blue). In the ΔCt mutant α-13 is missing, apparently destabilizing the mJHBP-JH III complex. B. Binding site detail showing hydrogen bonding between the Tyr129 hydroxyl group and the JH III epoxy group. This residue is mutated to phenylalanine in the Y129F and VFYF mutants. In the VFYF mutant Val68 is also mutated to phenylalanine (magenta), further occluding the binding pocket. C. Three site-directed mutants of mJHBP were evaluated for interaction with JH III using isothermal titration calorimetry (ITC). Traces showing heats of interaction reveal highly enthalpic binding of JH III with the WT protein. Injection heats decrease with increasing modification of the protein (WT > Y129F > VFYF > ΔCt).