title: Direct and inverted DNA repeats associated with P-glycoprotein gene amplification in drug resistant Leishmania.
abstract: The H circle of Leishmania species contains a 30 kb inverted duplication separated by two unique DNA segments, a and b. The corresponding H region of chromosomal DNA has only one copy of the duplicated DNA. We show here that the chromosomal segments a and b are flanked by inverted repeats (198 and 1241 bp) and we discuss how these repeats could lead to formation of H circles from chromosomal DNA. Selection of Leishmania tarentolae for methotrexate resistance indeed resulted in the de novo formation of circles with long inverted duplication, but two mutants selected for arsenite resistance contained new H region plasmids without such duplications. One of these plasmids appears due to a homologous recombination between two P-glycoprotein genes with a high degree of sequence homology. Our results show how the same DNA region in Leishmania may be amplified to give plasmids with or without long inverted duplications and apparently by different mechanisms.
authors.affiliation: Division of Molecular Biology, Netherlands Cancer Institute, Amsterdam.
authors.forename: M
authors.initials: M
authors.lastname: Ouellette
authors.forename: E
authors.initials: E
authors.lastname: Hettema
authors.forename: D
authors.initials: D
authors.lastname: Wüst
authors.forename: F
authors.initials: F
authors.lastname: Fase-Fowler
authors.forename: P
authors.initials: P
authors.lastname: Borst
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA; D004270:DNA, Circular / Q000235:genetics*; D016054:DNA, Protozoan / Q000235:genetics*; D004351:Drug Resistance / Q000235:genetics; D005784:Gene Amplification; D007891:Leishmania / Q000187:drug effects / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000235:genetics*; D008727:Methotrexate / Q000494:pharmacology; D008969:Molecular Sequence Data; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004270:DNA, Circular; D016054:DNA, Protozoan; D008562:Membrane Glycoproteins; D004247:DNA; D008727:Methotrexate