Figure 3.

1.95 Å structure of E. faecalis mvaS covalently modified by hymeglusin. Crystals of E. faecalis mvaS that had been briefly incubated with hymeglusin were produced as described in methods and used to collect monochromatic diffraction data. Following structure solution by molecular replacement, electron density maps were calculated that allowed modeling of bound ligand in each of the four crystallographically independent active sites. (A) Stereogram of the mvaS active site for chain A. Protein backbone is depicted in cartoon format (purple), while the sidechains of Glu⁷⁹, Tyr¹⁴³, and His²³³ are shown as cyan sticks. The catalytic Cys¹¹¹ is colored green, and carbon atoms of covalently-bound hymeglusin are colored yellow. 2F_o-F_c map (blue mesh at 1.1σ contour) of the refined structure corresponding to the Cys¹¹¹ thiolate-hymeglusin adduct is also shown. (B) Overlay of hymeglusin molecules as modeled in chains A-D, colored blue, green, orange, and red, respectively. The position of C8, which forms a covalent bond with the thiolate sulfur derived from Cys¹¹¹, is indicated with an arrow. Additional information for all four active sites can be found in Supplemental Figures 2–4.