| Abstrakt: |
ABSTRACTThe mechanisms underlying the drug resistance of Leishmaniaspp. are manifold and not completely identified. Apart from the highly conserved multidrug resistance gene family known from higher eukaryotes, Leishmaniaspp. also possess genus-specific resistance marker genes. One of them, ARM58, was first identified in Leishmania braziliensisusing a functional cloning approach, and its domain structure was characterized in L. infantum. Here we report that L. infantumARM58 is part of a gene cluster at the telomeric end of chromosome 34 also comprising the neighboring genes ARM56 and HSP23. We show that overexpression of all three genes can confer antimony resistance to intracellular amastigotes. Upon overexpression in L. donovani, ARM58 and ARM56 are secreted via exosomes, suggesting a scavenger/secretion mechanism of action. Using a combination of functional cloning and next-generation sequencing, we found that the gene cluster was selected only under antimonyl tartrate challenge and weakly under Cu2+challenge but not under sodium arsenite, Cd2+, or miltefosine challenge. The selective advantage is less pronounced in intracellular amastigotes treated with the sodium stibogluconate, possibly due to the known macrophage-stimulatory activity of this drug, against which these resistance markers may not be active. Our data point to the specificity of these three genes for antimony resistance. |
