title: Functional cloning of the miltefosine transporter. A novel P-type phospholipid translocase from Leishmania involved in drug resistance.
abstract: The antitumor drug miltefosine (hexadecylphosphocholine, MIL) has recently been approved as the first oral agent for the treatment of visceral leishmaniasis. Little is known about the mechanisms of action and uptake of MIL in either parasites or tumor cell lines. We have cloned a putative MIL transporter (LdMT) by functional rescue, using a Leishmania donovani-resistant line defective in the inward-directed translocation of both MIL and glycerophospholipids. LdMT is a novel P-type ATPase belonging to the partially characterized aminophospholipid translocase subfamily. Resistant parasites transfected with LdMT regain their sensitivity to MIL and edelfosine and the ability to normally take up [14C]MIL and fluorescent-labeled glycerophospholipids. Moreover, LdMT localizes to the plasma membrane, and its overexpression in Leishmania tarentolae, a species non-sensitive to MIL, significantly increases the uptake of [14C]MIL, strongly suggesting that this protein behaves as a true translocase. Finally, both LdMT-resistant alleles encompass single but distinct point mutations, each of which impairs transport function, explaining the resistant phenotype. These results demonstrate biochemically and genetically the direct involvement of LdMT in MIL and phospholipids translocation in Leishmania and describe for the first time a P-type ATPase involved in MIL uptake and potency in eukaryotic cells.
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics* / Q000502:physiology; D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D000981:Antiprotozoal Agents / Q000494:pharmacology; D001692:Biological Transport; D015139:Blotting, Southern; D002352:Carrier Proteins / Q000737:chemistry*; D002462:Cell Membrane / Q000378:metabolism; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003360:Cosmids; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D005838:Genotype; D015151:Immunoblotting; D007893:Leishmania donovani / Q000201:enzymology*; D008565:Membrane Proteins / Q000737:chemistry*; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics* / Q000502:physiology; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010641:Phenotype; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010742:Phospholipid Ethers / Q000494:pharmacology; D049294:Phospholipid Transfer Proteins; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D017354:Point Mutation; D015800:Protozoan Proteins; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
chemical_list: D000981:Antiprotozoal Agents; D002352:Carrier Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D010726:Phosphodiesterase Inhibitors; D010742:Phospholipid Ethers; D049294:Phospholipid Transfer Proteins; D015800:Protozoan Proteins; D012333:RNA, Messenger; D010767:Phosphorylcholine; C026659:edelfosine; C039128:miltefosine; D000251:Adenosine Triphosphatases; C480230:miltefosine transporter, Leishmania donovani