Institute of Microbiology, University of Greifswaldgrid.5603.0, Greifswald, Germany.
Institute of Marine Biotechnology, Greifswald, Germany.
mSphere. 2022 Oct 26;7(5):e0030222. doi: 10.1128/msphere.00302-22. Epub 2022 Aug 22.
Amidochelocardin is a broad-spectrum antibiotic with activity against many Gram-positive and Gram-negative bacteria. According to recent data, the antibiotic effect of this atypical tetracycline is directed against the cytoplasmic membrane, which is associated with the dissipation of the membrane potential. Here, we investigated the effect of amidochelocardin on the proteome of Clostridioides difficile to gain insight into the membrane stress physiology of this important anaerobic pathogen. For the first time, the membrane-directed action of amidochelocardin was confirmed in an anaerobic pathogen. More importantly, our results revealed that aromatic compounds potentially play an important role in C. difficile upon dissipation of its membrane potential. More precisely, a simultaneously increased production of enzymes required for the synthesis of chorismate and two putative phenazine biosynthesis proteins point to the production of a hitherto unknown compound in response to membrane depolarization. Finally, increased levels of the ClnAB efflux system and its transcriptional regulator ClnR were found, which were previously found in response to cationic antimicrobial peptides like LL-37. Therefore, our data provide a starting point for a more detailed understanding of C. difficile way to counteract membrane-active compounds. C. difficile is an important anaerobe pathogen causing mild to severe infections of the gastrointestinal tract. To avoid relapse of the infection following antibiotic therapy, antibiotics are needed that efficiently eradicate C. difficile from the intestinal tract. Since C. difficile was shown to be substantially sensitive to membrane-active antibiotics, it has been proposed that membrane-active antibiotics might be promising for the therapy of C. difficile infections. Therefore, we studied the response of C. difficile to amidochelocardin, a membrane-active antibiotic dissipating the membrane potential. Interestingly, C. difficile response to amidochelocardin indicates a role of aromatic metabolites in mediating stress caused by dissipation of the membrane potential.
氨曲南是一种广谱抗生素,对许多革兰氏阳性和革兰氏阴性细菌都有活性。根据最近的数据,这种非典型四环素的抗生素作用是针对细胞质膜的,这与膜电位的耗散有关。在这里,我们研究了氨曲南对艰难梭菌蛋白质组的影响,以深入了解这种重要的厌氧病原体的膜应激生理学。这是首次在厌氧病原体中证实了氨曲南对膜的作用。更重要的是,我们的结果表明,芳香族化合物在艰难梭菌的膜电位耗散时可能发挥重要作用。更确切地说,同时增加了用于合成分支酸的酶和两个假定的吩嗪生物合成蛋白的产生,表明在膜去极化时产生了一种迄今未知的化合物。最后,发现 ClnAB 外排系统及其转录调节剂 ClnR 的水平增加,这在以前的研究中发现是对阳离子抗菌肽如 LL-37 的反应。因此,我们的数据为更详细地了解艰难梭菌对抗膜活性化合物的方式提供了一个起点。艰难梭菌是一种重要的厌氧菌病原体,可引起胃肠道的轻度至重度感染。为了避免抗生素治疗后感染的复发,需要使用能够有效地从肠道中清除艰难梭菌的抗生素。由于艰难梭菌对膜活性抗生素有明显的敏感性,因此有人提出,膜活性抗生素可能是治疗艰难梭菌感染的有希望的药物。因此,我们研究了艰难梭菌对膜活性抗生素氨曲南的反应,该抗生素会耗散膜电位。有趣的是,艰难梭菌对氨曲南的反应表明,芳香族代谢物在介导膜电位耗散引起的应激中起作用。