Fig. 6.
The N-terminal 18 residues of VipD are essential for its PLA activity. (A) Fit of the optimized crystallographic VipD1–564-Rab5c18–182(Q80L) model (red line) to the experimental SAXS data of the complex (blue dots). (B) Fitting of the VipD19–564-Rab5c18–182(Q80L) crystallographic model (VipD in slate and Rab5 in pink) into the averaged ab initio envelope in two orthogonal views and superimposed with the unbound form of VipD (PDB 4AKF) in gray. Note the proximity of the N18 (residues 1–18 of VipD, PDB 4AKF) in red to the catalytic site. (C) Fluorescence-based PLA activity assays showing that the N18 segment of VipD is essential for its PLA1 activity.