A soluble pyrophosphatase, a key enzyme for polyphosphate metabolism in Leishmania.
We report the functional characterization in Leishmania amazonensis of a soluble pyrophosphatase (LaVSP1) that localizes in acidocalcisomes, a vesicular acidic compartment. LaVSP1 is preferentially expressed in metacyclic forms. Experiments with dominant negative mutants show the requirement of LaVSP1 functional expression for metacyclogenesis and virulence in mice. Depending on the pH and the cofactors Mg2+ or Zn2+, both present in acidocalcisomes, LaVSP1 hydrolyzes either inorganic pyrophosphate (Km = 92 microM, kcat = 125 s(-1)), tripolyphosphate (Km = 1153 microM, kcat = 131 s(-1)), or polyphosphate of 28 residues (Km = 123 microM, kcat = 8 s(-1)). Predicted structural analysis suggests that the structural orientation of the residue Lys78 in LaVSP1 accounts for the observed increase in Km compared with the yeast pyrophosphatase and for the ability of trypanosomatid VSP1 enzymes to hydrolyze polyphosphate. These results make the VSP1 enzyme an attractive drug target against trypanosomatid parasites.
Espiau
Benoît
B
Laboratoire de Génomique Fonctionnelle des Trypanosomatides, Université Victor Segalen Bordeaux 2, UMR-CNRS 5162, 146 rue Léo Saignat, 33076 Bordeaux, France.
Lemercier
Guillaume
G
Ambit
Audrey
A
Bringaud
Frédéric
F
Merlin
Gilles
G
Baltz
Théo
T
Bakalara
Norbert
N
D000818:Animals; D003001:Cloning, Molecular; D017931:DNA Primers; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D007700:Kinetics; D007891:Leishmania / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011122:Polyphosphates / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism*
D017931:DNA Primers; D011122:Polyphosphates; D015800:Protozoan Proteins; D011755:Pyrophosphatases