Biochemical characterization and crystallographic structure of an Escherichia coli protein from the phosphotriesterase gene family

Jenny L. Buchbinder, Robert C. Stephenson, Mark J. Dresser, Jed W. Pitera, Thomas (Tom) Scanlan, Robert J. Fletterick

Research output: Contribution to journalArticle

48 Scopus citations


Phosphotriesterase homology protein (PHP) is a member of a recently discovered family of proteins related to phosphotriesterase, a hydrolytic, bacterial enzyme with an unusual substrate specificity for synthetic organophosphate triesters and phosphorofluoridates, which are common constituents of chemical warfare agents and agricultural pesticides. No natural substrate has been identified for phosphotriesterase, and it has been suggested that the enzyme may have evolved the ability to hydrolyze synthetic compounds in bacteria under selective pressure to meet nutritional needs. PHP, which has 28% sequence identity with phosphotriesterase, may belong to the family of proteins from which phosphotriesterase evolved. Here we report the cloning, expression, initial characterization, and high-resolution X-ray crystallographic structure of PHP. Biochemical analysis shows that PHP is monomeric and binds two zinc ions per monomer. Unlike phosphotriesterase, PHP does not catalyze the hydrolysis of nonspecific phosphotriesters. The structure, similar to that of phosphotriesterase, consists of a long, elliptical α/β barrel and has a binuclear zinc center in a cleft at the carboxy end of the barrel at the location of the presumptive active site.

Original languageEnglish (US)
Pages (from-to)5096-5106
Number of pages11
Issue number15
Publication statusPublished - Apr 14 1998
Externally publishedYes


ASJC Scopus subject areas

  • Biochemistry

Cite this