Increased transport of pteridines compensates for mutations in the high affinity folate transporter and contributes to methotrexate resistance in the protozoan parasite Leishmania tarentolae

被引:81
作者
Kündig, C [1 ]
Haimeur, A [1 ]
Légaré, D [1 ]
Papadopoulou, B [1 ]
Ouellette, M [1 ]
机构
[1] CHUQ, Ctr Rech & Infectiol, Quebec City, PQ G1V 4G2, Canada
关键词
biopterin; drug resistance; folate transport; Leishmania; methotrexate;
D O I
10.1093/emboj/18.9.2342
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Functional cloning led to the isolation of a novel methotrexate (MTX) resistance gene in the protozoan parasite Leishmania. The gene corresponds to orfG, an open reading frame (ORF) of the LD1/CD1 genomic locus that is frequently amplified in several Leishmania stocks, A functional ORF G-green fluorescence protein fusion was localized to the plasma membrane, Transport studies indicated that ORF G is a high affinity biopterin transporter. ORF G also transports folic acid, with a lower affinity, but does not transport the drug analog MTX. Disruption of both alleles of orfG led to a mutant strain that became hypersensitive to MTX and had no measurable biopterin transport. Leishmania tarentolae MTX-resistant cells without their high affinity folate transporters have a rearranged orfG gene and increased orfG RNA levels. Overexpression of orfG leads to increased biopterin uptake and, in folate-rich medium, to increased folate uptake, MTX-resistant cells compensate for mutations in their high affinity folate/MTX transporter by overexpressing ORF G, which increases the uptake of pterins and selectively increases the uptake of folic acid, but not MTX.
引用
收藏
页码:2342 / 2351
页数:10
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