1w2m
Ca-substituted form of E. coli aminopeptidase P
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe effect of metal substitution on the activity and structure of the aminopeptidase P (APPro) from Escherichia coli has been investigated. Measurements of activity in the presence of Mn2+, Mg2+, Zn2+, Na+, and Ca2+ show that significant activity is seen only in the Mn-bound form of the enzyme. The addition of Zn2+ to [MnMn(APPro)] is strongly inhibitory. Crystal structures of [MnMn(APPro)], [MgMg(APPro)], [ZnZn(APPro)], [ZnMg(APPro)], [Ca_(APPro)], [Na_(APPro)], and [apo(APPro)] were determined. The structures of [Ca_(APPro)] and [Na_(APPro)] have a single metal atom at their active site. Surprisingly, when a tripeptide substrate (ValProLeu) was soaked into [Na_(APPro)] crystals in the presence of 200 mM Mg2+, the structure had substrate, but no metal, bound at the active site. The structure of apo APPro complexed with ValProLeu shows that the N-terminal amino group of a substrate can be bound at the active site by carboxylate side chains that normally bind the second metal atom, providing a model for substrate binding in a single-metal active enzyme. Structures of [MnMn(APPro)] and [ZnZn(APPro)] complexes of ProLeu, a product inhibitor, in the presence of excess Zn reveal a third metal-binding site, formed by two conserved His residues and the dipeptide inhibitor. A Zn atom bound at such a site would stabilize product binding and enhance inhibition. Structural and functional implications of metal ion selection in aminopeptidase P, a metalloprotease with a dinuclear metal center.,Graham SC, Bond CS, Freeman HC, Guss JM Biochemistry. 2005 Oct 25;44(42):13820-36. PMID:16229471[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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