School of Pharmacy and Medical Sciences, Griffith Universitygrid.1022.1, Gold Coast, Queensland, Australia.
Menzies Health Institute Queensland, Griffith Universitygrid.1022.1, Gold Coast, Queensland, Australia.
J Bacteriol. 2022 May 17;204(5):e0006822. doi: 10.1128/jb.00068-22. Epub 2022 Apr 11.
In bacteria, copper (Cu) can support metabolic processes as an enzymatic cofactor but can also cause cell damage if present in excess, leading to intoxication. In group B Streptococcus (GBS), a system for control of Cu efflux based on the prototypical operon supports survival during Cu stress. In some other bacteria, genetic systems additional to the operon are engaged during Cu stress and also contribute to the management of cellular Cu homeostasis. Here, we examined genetic systems beyond the operon in GBS for regions that contribute to survival of GBS in Cu stress using a forward genetic screen and probe of the entire bacterial genome. A high-density mutant library, generated using pGh9-IS, was used to expose GBS to Cu stress and compare it to nonexposed controls . Eight genes were identified as essential for GBS survival in Cu stress, whereas five genes constrained GBS growth in Cu stress. The genes encode varied factors including enzymes for metabolism, cell wall synthesis, transporters, and cell signaling factors. Targeted mutation of the genes validated their roles in GBS resistance to Cu stress. Excepting , the genes identified are new to the area of bacterial metal ion intoxication. We conclude that a discrete and limited suite of genes beyond the operon in GBS contributes to a repertoire of mechanisms used to survive Cu stress and achieve cellular homeostasis. Genetic systems for copper (Cu) homeostasis in bacteria, including streptococci, are vital to survive metal ion stress. Genetic systems that underpin survival of GBS during Cu stress, beyond the archetypal operon for Cu management, are undefined. We show that Streptococcus resists Cu intoxication by utilizing a discrete and limited suite of genes beyond the operon, including several genes that are new to the area of bacterial cell metal ion homeostasis. The Cu resistome of GBS defined here enhances our understanding of metal ion homeostasis in GBS.
在细菌中，铜 (Cu) 可以作为酶辅因子支持代谢过程，但如果过量存在，也会导致细胞损伤，从而引起中毒。在 B 群链球菌 (GBS) 中，基于典型的 operon 的铜外排控制体系支持其在铜应激下的存活。在其他一些细菌中，除了 operon 之外，还有其他遗传系统在铜应激时被激活，并且有助于管理细胞内铜稳态。在这里，我们使用正向遗传筛选和全基因组探针检查了 GBS 中除 operon 之外的遗传系统，以研究其在铜应激下对 GBS 存活的贡献。使用 pGh9-IS 生成的高密度突变文库被用于暴露 GBS 于铜应激下，并与非暴露对照进行比较。确定了八个基因对于 GBS 在铜应激下的存活是必需的，而五个基因则限制了 GBS 在铜应激下的生长。这些基因编码了各种因子，包括代谢、细胞壁合成、转运蛋白和细胞信号因子的酶。对这些基因的靶向突变验证了它们在 GBS 抵抗铜应激中的作用。除了 之外，所鉴定的基因在细菌金属离子中毒领域都是新的。我们得出的结论是，GBS 中除了 operon 之外的一组离散且有限的基因有助于一系列用于应对铜应激并实现细胞内稳态的机制。细菌（包括链球菌）中铜 (Cu) 稳态的遗传系统对于金属离子应激下的存活至关重要。除了用于铜管理的典型 operon 之外，支撑 GBS 在铜应激下存活的遗传系统尚未确定。我们表明，链球菌通过利用除了 operon 之外的一组离散且有限的基因来抵抗铜中毒，包括几个在细菌细胞金属离子稳态领域的新基因。这里定义的 GBS 的 Cu 抗性组增强了我们对 GBS 中金属离子稳态的理解。
