Identification of novel diphenyl urea inhibitors of Mt-GuaB2 active against Mycobacterium tuberculosis
Identification of novel diphenyl urea inhibitors of Mt-GuaB2 active against Mycobacterium tuberculosis
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DOI：
10.1099/mic.0.042549-0
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发表时间：
2011-01-01
期刊：
影响因子：
2.8
通讯作者：
Besra, Gurdyal S.
中科院分区：
文献类型：
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作者：
Usha, Veeraraghavan;Gurcha, Sudagar S.;Besra, Gurdyal S.
与大多数细菌只携带一个肌苷单磷酸脱氢酶（IMPDH）基因不同，结核分枝杆菌H37Rv的基因组序列预测了三个编码IMPDH的基因：guaB1、guaB2和guaB3。克隆这三个基因并在大肠杆菌中表达，以评价功能性IMPDH活性。纯化后的重组Mt-GuaB2，以磷酸肌苷为底物，被鉴定为结核分枝杆菌中唯一有活性的GuaB同源物，在pH 8.5和37℃下表现出最佳活性。Mt-GuaB2在体外被一组基于二苯基脲的衍生物显著抑制，这些衍生物也是抗结核分枝杆菌和臭垢分枝杆菌的有效药物，mic在0.2-0.5 μ g ml（-1）范围内。当Mt-GuaB2在垢垢分枝杆菌的反式质粒上过表达时，二苯基尿素类似物显示MIC增加16倍。有趣的是，当Mt-GuaB同源物（Mt-GuaB1和3）也在粪垢分枝杆菌的反式质粒上过表达时，它们也会产生耐药性，这表明尽管这些Mt-GuaB同源物在体外无活性，但它们可能会滴定活性化合物在体内的抑制特性。
In contrast with most bacteria, which harbour a single inosine monophosphate dehydrogenase (IMPDH) gene, the genomic sequence of Mycobacterium tuberculosis H37Rv predicts three genes encoding IMPDH: guaB1, guaB2 and guaB3. These three genes were cloned and expressed in Escherichia coli to evaluate functional IMPDH activity. Purified recombinant Mt-GuaB2, which uses inosine monophosphate as a substrate, was identified as the only active GuaB orthologue in M. tuberculosis and showed optimal activity at pH 8.5 and 37 degrees C. Mt-GuaB2 was inhibited significantly in vitro by a panel of diphenyl urea-based derivatives, which were also potent anti-mycobacterial agents against M. tuberculosis and Mycobacterium smegmatis, with MICs in the range of 0.2-0.5 mu g ml(-1). When Mt-GuaB2 was overexpressed on a plasmid in trans in M. smegmatis, a diphenyl urea analogue showed a 16-fold increase in MIC. Interestingly, when Mt-GuaB orthologues (Mt-GuaB1 and 3) were also overexpressed on a plasmid in trans in M. smegmatis, they also conferred resistance, suggesting that although these Mt-GuaB orthologues were inactive in vitro, they presumably titrate the effect of the inhibitory properties of the active compounds in vivo.