Thiostrepton Hijacks Pyoverdine Receptors To Inhibit Growth of Pseudomonas aeruginosa
Thiostrepton Hijacks Pyoverdine Receptors To Inhibit Growth of Pseudomonas aeruginosa
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DOI：
10.1128/aac.00472-19
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发表时间：
2019-09-01
影响因子：
4.9
通讯作者：
Burrows, Lori L.
中科院分区：
文献类型：
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作者：
Ranieri, Michael R. M.;Chan, Derek C. K.;Burrows, Lori L.
铜绿假单胞菌是一种形成生物膜的机会性病原体，对许多抗生素具有内在耐药性。在对调节生物膜形成的分子的高通量筛选中，我们发现硫肽类抗生素硫链丝菌肽（TS）被认为对革兰氏阴性菌没有活性，它以剂量依赖性方式刺激铜绿假单胞菌生物膜的形成。这种表型是暴露于亚抑制浓度的抗菌化合物的特征，表明 TS 对铜绿假单胞菌具有活性。 TS 在低微摩尔浓度下抑制了一组 96 种多重耐药 (MDR) 铜绿假单胞菌临床分离株的生长，支持了这一观察结果。 TS 还具有对抗鲍曼不动杆菌临床分离株的活性。 Tsr（一种来自 TS 生产者天蓝色链霉菌的 23S rRNA 修饰甲基转移酶）的反式表达赋予 TS 抗性，证实该药物通过其典型的作用模式（抑制核糖体功能）发挥作用。其他肽类抗生素用于吸收的寡肽通透酶系统的缺失未能赋予 TS 抗性。 TS 敏感性与铁的利用率成反比，这表明 TS 利用了在铁饥饿时表达增加的摄取途径。与这一发现一致，FDA 批准的铁螯合剂去铁酮和地拉罗司以及热灭活血清增强了 TS 对铜绿假单胞菌和鲍曼不动杆菌的活性。对铜绿假单胞菌突变体的 TS 抗性筛选表明，它利用 pyoverdine 受体 FpvA 和 FpvB 穿过外膜。我们表明，生物膜刺激表型可以揭示隐秘的亚抑制性抗生素活性，并且 TS 在铁限制的生长条件下具有对抗选定的多重耐药革兰氏阴性病原体的活性，类似于感染部位遇到的情况。
Pseudomonas aeruginosa is a biofilm-forming opportunistic pathogen and is intrinsically resistant to many antibiotics. In a high-throughput screen for molecules that modulate biofilm formation, we discovered that the thiopeptide antibiotic thiostrepton (TS), which is considered to be inactive against Gram-negative bacteria, stimulated P. aeruginosa biofilm formation in a dose-dependent manner. This phenotype is characteristic of exposure to antimicrobial compounds at subinhibitory concentrations, suggesting that TS was active against P. aeruginosa. Supporting this observation, TS inhibited the growth of a panel of 96 multidrug-resistant (MDR) P. aeruginosa clinical isolates at low-micromolar concentrations. TS also had activity against Acinetobacter baumannii clinical isolates. The expression of Tsr, a 23S rRNA-modifying methyltransferase from TS producer Streptomyces azureus, in trans conferred TS resistance, confirming that the drug acted via its canonical mode of action, inhibition of ribosome function. The deletion of oligopeptide permease systems used by other peptide antibiotics for uptake failed to confer TS resistance. TS susceptibility was inversely proportional to iron availability, suggesting that TS exploits uptake pathways whose expression is increased under iron starvation. Consistent with this finding, TS activity against P. aeruginosa and A. baumannii was potentiated by the FDA-approved iron chelators deferiprone and deferasirox and by heat-inactivated serum. Screening of P. aeruginosa mutants for TS resistance revealed that it exploits pyoverdine receptors FpvA and FpvB to cross the outer membrane. We show that the biofilm stimulation phenotype can reveal cryptic subinhibitory antibiotic activity, and that TS has activity against select multidrug-resistant Gram-negative pathogens under iron-limited growth conditions, similar to those encountered at sites of infection.