The characterization of two novel PTP-enzymes from Bdellovibrio bacteriovorus and Pseudomonas syringae pv. tomato DC3000

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Thibault, John L
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2010
Recently, a new group of phytate degrading enzymes has been isolated from anaerobic bacteria from the rumen. This enzyme group is characterized by a protein tyrosine phosphatase (PTP) -like active site signature sequence. Searches of genetic databases have identified over 40 homologues to this group of phytate-degrading enzymes in a wide variety of bacterial species. To further our understanding of this enzyme group, two new representative genes from Bdellovibrio bacteriovorus and Pseudomonas syringae pv. tomato DC3000 were overexpressed and their recombinant gene products examined. B. bacteriovorus is a bacterium that preys on other Gram negative bacteria while P. syringae DC3000 is a phytopathogen that infects a variety of plant species. A combination of biochemical, kinetic and site-directed mutagenesis analyses demonstrated that these enzymes dephosphorylate phytic acid (InsP6) following a classical PTP mechanism, and have a high specificity for InsP6. The biological function of these enzymes was studied by over producing HopAO1 and HopAO1 C378S in Saccharomyces cerevisiae. HopAO1 inhibited growth of the yeast while the catalytically inactive HopAO1 C378S mutant had no effect. Future studies with this system will shed light on the biological function of HopAO1, PhyAbb and other PTP-like phytate degrading enzymes.
ix, 95 leaves ; 29 cm
Phytate degrading enzymes , PTP-like enzymes , Bdellovibrio bacteriovorus , Pseudomonas syringae pv. tomato DC3000 , Dissertations, Academic