Effect of carboxylate-binding mode on metal binding/selectivity and function in proteins

We delineate the factors governing the carboxylate-binding mode ( monodentate vs bidentate) in metalloproteins. We reveal how the carboxylate-binding mode affects the binding affinity and selectivity of a metal ion as well as the function of a metalloprotein using Ca2+-binding proteins and enzymes ( ribonuclease H1, phosphoserine phosphatase, and ribonucleotide reductase) as examples. The collected data indicate that a carboxylate monodentate reversible arrow bidentate switch, in addition to other structural factors, could be used to fine tune the metal-binding site affinity and/or selectivity, thus modifying the function/properties of the metalloprotein.