Reduced transcription of the ferredoxin gene in metronidazole-resistant Trichomonas vaginalis.
Reduced transcription of the ferredoxin gene in metronidazole-resistant Trichomonas vaginalis.
复制标题
甲硝唑耐药性阴道毛滴虫中铁氧还蛋白基因的转录减少。
DOI：
10.1073/pnas.89.10.4402
复制
发表时间：
1992
影响因子：
11.1
通讯作者：
Johnson,PJ
中科院分区：
文献类型：
--
作者：
Quon,DV;d'Oliveira,CE;Johnson,PJ
甲硝唑[1-（2-羟乙基）-2-甲基-5-硝基咪唑]用于治疗阴道毛滴虫（一种性传播的人类寄生虫）引起的感染。该药物以非活性形式给药，并在氢小体内还原为细胞毒性形式，氢小体是毛滴虫中发现的一种不寻常的细胞器。甲硝唑还原通过铁氧还蛋白介导的电子传递发生。我们研究了铁氧还蛋白在甲硝唑耐药中的作用。耐药和敏感T.迷走神经炎菌株显示，相对于敏感菌株，在抗性菌株中铁氧还蛋白的细胞内水平总是降低。类似地，北方印迹分析显示铁氧还蛋白mRNA水平在抗性菌株中降低50-65%。使用核运行分析，我们表明，铁氧还蛋白基因转录减少40-65%的耐药菌株。药物敏感株和耐药株之间的铁氧还蛋白基因5'区的序列比较揭示了在耐药株中相对于转录起始的-178和-239个核苷酸处的两个点突变。有趣的是，约23 kDa的蛋白质结合到包含约239个核苷酸处的突变的28个碱基对区域。该蛋白的结合亲和力似乎在突变体中降低。这些数据强烈地将耐药性与铁氧还蛋白基因转录调节的改变相关联。基因转录的减少导致铁氧还蛋白的细胞内水平降低。反过来，这可能通过降低细胞激活药物的能力而在甲硝唑耐药性中发挥作用。
Metronidazole [1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole] is used to treat infections caused by Trichomonas vaginalis, a sexually transmitted human parasite. This drug is administered in an inactive form and is reduced to its cytotoxic form within the hydrogenosome, an unusual organelle found in trichomonads. Metronidazole reduction occurs via ferredoxin-mediated electron transport. We have investigated the role of ferredoxin in metronidazole resistance. Immunoblot analysis of drug-resistant and -sensitive T. vaginalis strains shows that intracellular levels of ferredoxin are invariably reduced in the resistant strains relative to a sensitive strain. Similarly, Northern blot analysis shows that ferredoxin mRNA levels are reduced 50-65% in resistant strains. Using nuclear run-on assays, we show that ferredoxin gene transcription is reduced 40-65% in resistant strains. Sequence comparison of the region 5' of the ferredoxin gene among drug-sensitive and -resistant strains reveals two point mutations, at -178 and -239 nucleotides relative to the start of transcription, in a resistant strain. Interestingly, a protein of approximately 23 kDa binds to a 28-base-pair region that encompasses the mutation at -239 nucleotides. The binding affinity of this protein appears to be reduced in the mutant. These data strongly correlate drug resistance with altered regulation of ferredoxin gene transcription. A reduction in gene transcription results in decreased intracellular levels of ferredoxin. This, in turn, may play a role in metronidazole resistance by decreasing the ability of the cell to activate the drug.
甲硝唑对阴道毛滴虫和其他微生物的作用方式。
影响因子：
5.8
作者：
R. Ings;J. McFadzean;W. Ormerod
通讯作者：
W. Ormerod