Properties of phosphoenolpyruvate mutase, the first enzyme in the aminoethylphosphonate biosynthetic pathway in Trypanosoma cruzi.
Phosphoenolpyruvate (PEP) mutase catalyzes the conversion of phosphoenolpyruvate to phosphonopyruvate, the initial step in the formation of many naturally occurring phosphonate compounds. The phosphonate compound 2-aminoethylphosphonate is present as a component of complex carbohydrates on the surface membrane of many trypanosomatids including glycosylinositolphospholipids of Trypanosoma cruzi. Using partial sequence information from the T. cruzi genome project we have isolated a full-length gene with significant homology to PEP mutase from the free-living protozoan Tetrahymena pyriformis and the edible mussel Mytilus edulis. Recombinant expression in Escherichia coli confirms that it encodes a functional PEP mutase with a Km apparent of 8 microM for phosphonopyruvate and a kcat of 12 s-1. The native enzyme is a homotetramer with an absolute requirement for divalent metal ions and displays negative cooperativity for Mg2+ (S0.5 0.4 microM; n = 0.46). Immunofluorescence and sub-cellular fractionation indicates that PEP mutase has a dual localization in the cell. Further evidence to support this was obtained by Western analysis of a partial sub-cellular fractionation of T. cruzi cells. Southern and Western analysis suggests that PEP mutase is unique to T. cruzi and is not present in the other medically important parasites, Trypanosoma brucei and Leishmania spp.
Sarkar
Mitali
M
Division of Biological Chemistry and Molecular Microbiology, The Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom.
Hamilton
Christopher J
CJ
Fairlamb
Alan H
AH
D000595:Amino Acid Sequence; D000615:Aminoethylphosphonic Acid / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D017875:Phosphotransferases (Phosphomutases) / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000201:enzymology; D014349:Trypanosoma cruzi / Q000201:enzymology*
D017261:Glycosylphosphatidylinositols; D000615:Aminoethylphosphonic Acid; D017875:Phosphotransferases (Phosphomutases); C057167:phosphoenolpyruvate mutase