The modeled structure of the YycG HATPase_c domain of S. epidermidis. (A) Structure superposition of the modeled structure of YycG HATPase_c domain of S. epidermidis (blue) with the NMR structure of the homologous domain of EnvZ in E. coli (yellow). Only backbones are shown in this picture. (B) The solid ribbon representation of the structure model of the YycG HATPase_c domain. The YycG HATPase_c domain of S. epidermidis folds into a two-layer sandwich structure. Four high conserved motifs, N-box (Asn499~Tyr507), G1-box (Ile53~Ile538), F-box (Asp544~Phe547), G2-box (Gly563~Gly567), around the catalytic domain of the HPK encompasses the active ATP-binding pocket and a long loop from Asp548 to Ala574 drifts outside the pocket. The substrate-binding site is located at the deep cleft among N, G1, F, G2 boxes. Schematic diagrams were made by the program Molscript.