Structural and functional analysis of an amplification containing a PGPA gene in a glucantime-resistant Leishmania (Viannia) guyanensis cell line

Drug resistance is a complex phenomenon in Leishmania and commonly involves gene amplification. Active efflux and metal sequestration through a P-glycoprotein have been pointed to as the major mechanisms used by drug-resistant Leishmania. A gene amplification from a glucantime-resistant Leishmania (Viannia) guyanensis cell line was characterised in an attempt to understand the mechanism of metal resistance in this pathogenic species. We show that the amplification is present as an extrachromosomal amplicon of 30 kb and contains a PGPA gene (LgPGPA), which is overexpressed in the resistant line as shown by Northern and Western blot analyses. In addition, we gathered evidence from transfection experiments for the role of the LgPGPA gene in oxyanion resistance in L. (V.) guyanensis. Our work indicates that, in this pathogenic New World Leishmania species, amplification of the PGPA gene is the major determinant in oxyanion resistance.