A Telomeric Cluster of Antimony Resistance Genes on Chromosome 34 of Leishmania infantum

• Published in: Antimicrobial agents and chemotherapy 2016-09, Vol.60 (9), p.5262-5275
• Main Authors: Tejera Nevado, Paloma, Bifeld, Eugenia, Höhn, Katharina, Clos, Joachim
• Format: Article
• Language: English
• Subjects: Antimony; Antimony - pharmacology; Antimony Sodium Gluconate - pharmacology; Antiprotozoal Agents; Antiprotozoal Agents - pharmacology; Cadmium - pharmacology; Cloning, Molecular; Copper - pharmacology; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; Drug Resistance; Drug Resistance - genetics; Exosomes - chemistry; Exosomes - drug effects; Exosomes - metabolism; Gene Expression; Heat-Shock Proteins - genetics; Heat-Shock Proteins - metabolism; High-Throughput Nucleotide Sequencing; Leishmania braziliensis; Leishmania infantum; Leishmania infantum - drug effects; Leishmania infantum - genetics; Leishmania infantum - growth & development; Leishmania infantum - metabolism; Life Cycle Stages - drug effects; Life Cycle Stages - genetics; Mechanisms of Resistance; Multigene Family; Phosphorylcholine - analogs & derivatives; Phosphorylcholine - pharmacology; Protozoan Proteins; Protozoan Proteins - genetics; Protozoan Proteins - secretion; Telomere; Telomere - chemistry; Telomere - metabolism
• ISSN: 0066-4804; 1098-6596
• DOI: 10.1128/AAC.00544-16

The mechanisms underlying the drug resistance of Leishmania spp. are manifold and not completely identified. Apart from the highly conserved multidrug resistance gene family known from higher eukaryotes, Leishmania spp. also possess genus-specific resistance marker genes. One of them, ARM58, was first identified in Leishmania braziliensis using a functional cloning approach, and its domain structure was characterized in L. infantum Here we report that L. infantum ARM58 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 Cu(2+) challenge but not under sodium arsenite, Cd(2+), 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.