Mechanisms of arsenical and diamidine uptake and resistance in Trypanosoma brucei
Mechanisms of arsenical and diamidine uptake and resistance in Trypanosoma brucei
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DOI：
10.1128/ec.2.5.1003-1008.2003
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发表时间：
2003-10-01
期刊：
影响因子：
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通讯作者：
de Koning, HP
中科院分区：
文献类型：
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作者：
Matovu, E;Stewart, ML;de Koning, HP
由布氏锥虫引起的昏睡病，在撒哈拉以南的非洲地区又死灰复燃。此外，用于治疗晚期昏睡病的主要药物美拉胂醇的治疗失败率惊人地增加。于t.在布氏杆菌中，认为美拉胂醇以及联脒的摄取由P2氨基嘌呤转运蛋白介导，P2功能的丧失与对这些药物的耐药性有关。已发现锥虫基因TbAT 1在酵母中表达时编码P2型转运蛋白。在此，我们研究TbAT 1在T.通过TbAT 1基因敲除获得了布鲁氏菌的TbAT 1基因。Tbat1-null锥虫缺乏P2型腺苷转运，缺乏对喷他脒和三聚氰胺苯砷的腺苷敏感转运。然而，无效突变体仅对三聚氰胺苯砷和喷他脒有轻微的抗性，而对其他二脒如diminazene的抗性更明显。然而，药物敏感性的降低可能具有临床意义，因为感染tbat1缺失锥虫的小鼠不能连续4天用2 mg/kg体重的美拉胂醇治愈，而感染亲本系的小鼠通过使用该方案全部治愈。两个额外的戊烷脒转运蛋白，RAPT1和LAPT1，仍然存在于无效突变体，和证据表明，RAPT1可能是负责三聚氰胺苯砷残留的摄取。因此，高水平的砷耐药性似乎涉及一种以上转运蛋白的丧失。
Sleeping sickness, caused by Trypanosoma brucei spp., has become resurgent in sub-Saharan Africa. Moreover, there is an alarming increase in treatment failures with melarsoprol, the principal agent used against late-stage sleeping sickness. In T. brucei, the uptake of melarsoprol as well as diamidines is thought to be mediated by the P2 aminopurine transporter, and loss of P2 function has been implicated in resistance to these agents. The trypanosomal gene TbAT1 has been found to encode a P2-type transporter when expressed in yeast. Here we investigate the role of TbAT1 in drug uptake and drug resistance in T. brucei by genetic knockout of TbAT1. Tbat1-null trypanosomes were deficient in P2-type adenosine transport and lacked adenosine-sensitive transport of pentamidine and melaminophenyl arsenicals. However, the null mutants were only slightly resistant to melaminophenyl arsenicals and pentamidine, while resistance to other diamidines such as diminazene was more pronounced. Nevertheless, the reduction in drug sensitivity might be of clinical significance, since mice infected with tbat1-null trypanosomes could not be cured with 2 mg of melarsoprol/kg of body weight for four consecutive days, whereas mice infected with the parental line were all cured by using this protocol. Two additional pentamidine transporters, RAPT1 and LAPT1, were still present in the null mutant, and evidence is presented that RAPT1 may be responsible for the residual uptake of melaminophenyl arsenicals. High-level arsenical resistance therefore appears to involve the loss of more than one transporter.