We report a catalytically promiscuous enzyme able to efficiently promote the hydrolysis of six different substrate classes. Originally assigned as a phosphonate monoester hydrolase (PMH) this enzyme exhibits substantial second-order rate accelerations ((kcat/KM) /k w), ranging from 107 to as high as 1019, for the hydrolyses of phosphate mono-, di-, and triesters, phosphonate monoesters, sulfate monoesters, and sulfonate monoesters. This substrate collection encompasses a range of substrate charges between 0 and -2, transition states of a different nature, and involves attack at two different reaction centers (P and S). Intrinsic reactivities (half-lives) range from 200 days to 105 years under near neutrality. The substantial rate accelerations for a set of relatively difficult reactions suggest that efficient catalysis is not necessarily limited to efficient stabilization of just one transition state. The crystal structure of PMH identifies it as a member of the alkaline phosphatase superfamily. PMH encompasses four of the native activities previously observed in this superfamily and extends its repertoire by two further activities, one of which, sulfonate monoesterase, has not been observed previously for a natural enzyme. PMH is thus one of the most promiscuous hydrolases described to date. The functional links between superfamily activities can be presumed to have played a role in functional evolution by gene duplication.
|Number of pages||6|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Early online date||27 Jan 2010|
|Publication status||Published - 16 Feb 2010|