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Publication Abstract from PubMed

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

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.,Jonas S, van Loo B, Hyvonen M, Hollfelder F J Mol Biol. 2008 Dec 5;384(1):120-36. Epub 2008 Sep 4. PMID:18793651^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.