Gene disruption of the P-glycoprotein related gene pgpa of Leishmania tarentolae.

Transfection of pgpA into Leishmania confers resistance to arsenite and antimonials. By gene targeting mediated by homologous recombination the two alleles of the pgpA gene of a L. tarentolae wild-type cell were disrupted sequentially with the neomycin and hygromycin phosphotransferase genes. This pgpA null mutant showed an increased sensitivity to arsenite and antimonite. In addition, the L. tarentolae pgpA null mutant exhibited a decreased intracellular survival inside murine macrophages. The observed phenotypes were reverted to levels not statistically different than wild-type when an intact pgpA gene was introduced into the null mutant. Disruption of the pgpA chromosomal locus in an arsenite resistant mutant indicated that PgpA is not essential for resistance to oxyanions, although it might be required in the early steps of selection when resistance is being established.