Structures of PhoRtcB in complexes with GTP and zinc or copper. Stereo views of the GTP•(Zn2+)2 (A) and GTP•(Cu2+)2 complexes (B) are shown. GTP is rendered as a cartoon model with gray carbons and yellow phosphorus atoms. Amino acids contacting GTP and metals are labeled and depicted as stick models with beige carbons. Atomic contacts are indicated by black dashed lines. The distance between the His404-Nε nucleophile and the GTP α-phosphorus is denoted by a magenta dashed line. Two Zn atoms (A) and Cu atoms (B) are rendered as orange spheres and green spheres, respectively. Anomalous difference peaks overlying the Zn and Cu atoms (blue mesh) are contoured at 15σ and 7σ, respectively.
