Keck Science Department, Scripps College, Claremont, California, USA.
Keck Science Department, Pitzer College, Claremont, California, USA.
Microbiol Spectr. 2022 Apr 27;10(2):e0132921. doi: 10.1128/spectrum.01329-21. Epub 2022 Mar 21.
Zinc and copper are essential micronutrients that serve as a cofactors for numerous enzymes. However, when present at elevated concentrations, zinc and copper are highly toxic to bacteria. To combat the effects of zinc and copper excess, bacteria have evolved a wide array of defense mechanisms. Here, we show that the Gram-positive soil bacterium, Bacillus subtilis, produces the extracellular polymeric substance, poly-gamma-glutamate (γ-PGA) as a protective mechanism in response to zinc and copper excess. Furthermore, we provide evidence that zinc and copper dependent γ-PGA production is independent of the DegS-DegQ two-component regulatory system and likely occurs at a posttranscriptional level through the small protein, PgsE. These data provide new insight into bacterial metal resistance mechanisms and contribute to our understanding of the regulation of bacterial γ-PGA biosynthesis. Zinc and copper are potent antimicrobial compounds. As such, bacteria have evolved a diverse range of tools to prevent metal intoxication. Here, we show that the Gram-positive model organism, Bacillus subtilis, produces poly-gamma-glutamic acid (γ-PGA) as a protective mechanism against zinc and copper intoxication and that zinc and copper dependent γ-PGA production occurs by a yet undefined mechanism independent of known γ-PGA regulation pathways.
锌和铜是必需的微量元素，作为许多酶的辅助因子。然而，当浓度升高时，锌和铜对细菌具有高度毒性。为了应对锌和铜过量的影响，细菌已经进化出了广泛的防御机制。在这里，我们表明革兰氏阳性土壤细菌枯草芽孢杆菌产生胞外多聚物聚-γ-谷氨酸（γ-PGA）作为应对锌和铜过量的保护机制。此外，我们提供的证据表明，锌和铜依赖性γ-PGA 产生不依赖于 DegS-DegQ 双组分调节系统，并且可能通过小蛋白 PgsE 在转录后水平发生。这些数据为细菌金属抗性机制提供了新的见解，并有助于我们理解细菌 γ-PGA 生物合成的调节。锌和铜是有效的抗菌化合物。因此，细菌已经进化出多种工具来防止金属中毒。在这里，我们表明革兰氏阳性模式生物枯草芽孢杆菌产生聚-γ-谷氨酸（γ-PGA）作为一种针对锌和铜中毒的保护机制，并且锌和铜依赖性 γ-PGA 产生发生的机制尚不清楚，独立于已知的 γ-PGA 调节途径。
