摘要：Detailed crystallographic characterization of a tri-aspartate metal-binding site previously identified on the three-fold symmetry axis of a hexameric enzyme, LarE from Lactobacillus plantarum, was conducted. By screening an array of monovalent, divalent, and trivalent metal ions, we demonstrated that this metal binding site stoichiometrically binds Ca2 , Mn2 , Fe2 /Fe3 , Co2 , Ni2 , Cu2 , Zn2 , and Cd2 , but not monovalent metal ions, Cr3 , Mg2 , Y3 , Sr2 or Ba2 . Extensive database searches resulted in only 13 similar metal binding sites in other proteins, indicative of the rareness of tri-aspartate architectures, which allows for engineering such a selective multivalent metal ion binding site into target macromolecules for structural and biophysical characterization.
