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. Author manuscript; available in PMC: 2011 May 18.
Published in final edited form as: Biochemistry. 2010 May 18;49(19):4276–4282. doi: 10.1021/bi100365b

FIGURE 3. Crystal structure of the dead-end complex of E. cloacae MurA with terreic acid.

FIGURE 3

(Top, stereoview) The overall structure of MurA inactivated by terreic acid exists in an open conformation and is free of UNAG. The loop hosting Cys115 is shown in magenta; the covalently bound terreic acid molecule (cyan) is largely solvent–exposed.

(Middle, stereoview) A detailed view of the Cys115-terreic acid adduct reveals multiple polar interactions (d ≤ 3.3 Å, black dotted lines) with water molecules (orange spheres) and two Ca2+ ions from the crystallization solution (green spheres); hydrophobic interactions (d ≤ 3.8 Å, green dotted lines) exist with Leu138. The blue-colored mesh represents the Fo-Fc difference electron density map (at 2.25 Å resolution and contoured at 3σ), omitting the modified Cys115 residue during the refinement.

(Bottom) Proposed chemical reaction of terreic acid with Cys115.