Zheng Xiao-Fu, Liu Xin-Qiang, Peng Shu-Ya, Zhou Qiang, Xu Bin, Yuan Hua, Tang Gong-Li
Department of Chemistry, College of Sciences, Shanghai University, Shanghai, China.
CAS-Key Laboratory of Synthetic Biology, Shanghai Institute of Plant Physiology and Ecology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China.
Front Microbiol. 2020 Jun 3;11:971. doi: 10.3389/fmicb.2020.00971. eCollection 2020.
Rifamycin derivatives, such as rifampicin, have potent antibiotic activity and have long been used in the clinic as mainstay components for the treatment of tuberculosis, leprosy, and AIDS-associated mycobacterial infections. However, the extensive usage of these antibiotics has resulted in the rapid development of bacterial resistance. The resistance mechanisms mainly include mutations of the rifamycin target RNA polymerase of bacteria and enzymatic modifications of rifamycin antibiotics. One modification is the recently characterized rifamycin degradation catalyzed by Rox enzymes, which belong to the widely occurring flavin monooxygenases. Intriguingly, our recent sequence analysis revealed the rifamycin producers also encode Rox homologs that are not yet characterized. In this work, we expanded the study of the Rox-catalyzed rifamycin degradation. We first showed that the Rox proteins from rifamycin producers have the enzymatic rifamycin SV-degrading activity. Then we used the structurally diverse rifamycin compounds rifampicin and 16-demethylrifamycin W to probe the substrate scope and found that they each have a slightly different substrate scope. Finally, we demonstrated that Rox proteins can also catalyze the transformation of 16-demethylsalinisporamycin to 16-demethylsaliniketal A. Since 16-demethylsalinisporamycin and 16-demethylsaliniketal A are the counterpart analogs of salinisporamycin and saliniketal A, our biochemical findings not only uncover a previously uncharacterized self-resistance mechanism in the rifamycin producers, but also bridge the gap between the biosynthesis of the potential antitumor compound saliniketal A.
利福霉素衍生物，如利福平，具有强大的抗生素活性，长期以来一直作为治疗结核病、麻风病和艾滋病相关分枝杆菌感染的主要成分在临床上使用。然而，这些抗生素的广泛使用导致了细菌耐药性的迅速发展。耐药机制主要包括细菌利福霉素靶标RNA聚合酶的突变和利福霉素抗生素的酶促修饰。一种修饰是最近发现的由Rox酶催化的利福霉素降解，Rox酶属于广泛存在的黄素单加氧酶。有趣的是，我们最近的序列分析表明，利福霉素产生菌也编码尚未被表征的Rox同源物。在这项工作中，我们扩展了对Rox催化的利福霉素降解的研究。我们首先表明，来自利福霉素产生菌的Rox蛋白具有酶促降解利福霉素SV的活性。然后我们使用结构多样的利福霉素化合物利福平和16-去甲基利福霉素W来探测底物范围，发现它们各自的底物范围略有不同。最后，我们证明Rox蛋白还可以催化16-去甲基盐霉素转化为16-去甲基盐霉素A。由于16-去甲基盐霉素和16-去甲基盐霉素A分别是盐霉素和盐霉素A的对应类似物，我们的生化研究结果不仅揭示了利福霉素产生菌中一种以前未被表征的自我耐药机制，而且还填补了潜在抗肿瘤化合物盐霉素A生物合成之间的空白。
