Molecular characterization of the ldmdr1 multidrug resistance gene from Leishmania donovani

Abstract

The ldmdr1 gene that confers resistance to multiple structurally dissimilar hydrophobic drugs in Leishmania donovani has been isolated within a 5.4-kb XmaI fragment from a genomic library of L. donovani DNA and its protein coding region sequenced. The longest open reading frame within ldmdr1 encodes a 146.5-kDa protein of 1341 amino acids, designated LDMDR1. The primary structure and predicted membrane topology of LDMDR1 indicates that it is a member of the P-glycoprotein superfamily with the greatest homology to the mammalian multidrug resistance P-glycoproteins. A 2.3-kb SalI fragment derived from a second ldmdr1 allele was also cloned from the L. donovani library. Nucleotide sequence analysis of a portion of the SalI insert revealed 5 single base differences from its counterpart within the 5.4-kb XmaI fragment, one of which created a PvuI restriction site polymorphism. Southern blots of PvuI-digested DNA divulged that the amplified ldmdr1 gene copies in a multidrug-resistant L. donovani strain were all derived from the single ldmdr1 allele whose protein coding segment was sequenced in its entirety.