A new activity for an old enzyme: Escherichia coli bacterial alkaline phosphatase is a phosphite-dependent hydrogenase | Zendy

Kechao Yang | Zendy; William W. Metcalf | Zendy

Open Access

A new activity for an old enzyme: Escherichia coli bacterial alkaline phosphatase is a phosphite-dependent hydrogenase

Author(s) -

Kechao Yang,

William W. Metcalf

Publication year - 2004

Publication title -

proceedings of the national academy of sciences

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 5.011

H-Index - 771

eISSN - 1091-6490

pISSN - 0027-8424

DOI - 10.1073/pnas.0400664101

Subject(s) - operon , escherichia coli , biochemistry , enzyme , alkaline phosphatase , phosphatase , transposon mutagenesis , hydrogenase , chemistry , biology , gene , transposable element , mutant

Genetic analysis indicates that Escherichia coli possesses two independent pathways for oxidation of phosphite (Pt) to phosphate. One pathway depends on the 14-gene phn operon, which encodes the enzyme C-P lyase. The other pathway depends on the phoA locus, which encodes bacterial alkaline phosphatase (BAP). Transposon mutagenesis studies strongly suggest that BAP is the only enzyme involved in the phoA-dependent pathway. This conclusion is supported by purification and biochemical characterization of the Pt-oxidizing enzyme, which was proven to be BAP by N terminus protein sequencing. Highly purified BAP catalyzed Pt oxidation with specific activities of 62-242 milliunits/mg and phosphate ester hydrolysis with specific activities of 41-61 units/mg. Surprisingly, BAP catalyzes the oxidation of Pt to phosphate and molecular H2. Thus, BAP is a unique Pt-dependent, H2-evolving hydrogenase. This reaction is unprecedented in both P and H biochemistry, and it is likely to involve direct transfer of hydride from the substrate to water-derived protons.

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