A new member of the alkaline phosphatase superfamily with a formylglycine nucleophile: structural and kinetic characterisation of a phosphonate monoester hydrolase/phosphodiesterase from Rhizobium leguminosarum.

摘要: Abstract The alkaline phosphatase superfamily comprises a large number of hydrolytic metalloenzymes such as phosphatases and sulfatases. We have characterised new member this superfamily, phosphonate monoester hydrolase/phosphodiesterase from Rhizobium leguminosarum (RlPMH) both structurally kinetically. 1.42 A crystal structure shows structural homology to arylsulfatases with conservation the core α/β-fold, mononuclear active site most active-site residues. Sulfatases use unique formylglycine nucleophile, formed by posttranslational modification cysteine/serine embedded in signature sequence (C/S)XPXR. provide mass spectrometric mutational evidence that RlPMH is first non-sulfatase enzyme shown catalytic nucleophile. hydrolyses monoesters phosphate diesters similar efficiency. Burst kinetics suggest substrate hydrolysis proceeds via double-displacement mechanism. Kinetic characterisation mutations establishes contributions individual A mechanism for proposed on basis kinetic data comparisons E. coli Pseudomonas aeruginosa arylsulfatase. represents further example overall within superfamily.