Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbournegrid.1008.9, Melbourne, Victoria, Australia.
Microbiol Spectr. 2022 Feb 23;10(1):e0177321. doi: 10.1128/spectrum.01773-21. Epub 2022 Jan 12.
Klebsiella pneumoniae is an opportunistic Gram-negative pathogen that is a leading cause of healthcare-associated infections, including pneumonia, urinary tract infections, and sepsis. Essential to the colonization and infection by K. pneumoniae is the acquisition of nutrients, such as the transition metal ion zinc. Zinc has crucial structural and catalytic roles in the proteome of all organisms. Nevertheless, in excess, it has the potential to mediate significant toxicity by dysregulating the homeostasis of other transition elements, disrupting enzymatic processes, and perturbing metalloprotein cofactor acquisition. Here, we sought to elucidate the zinc detoxification mechanisms of K. pneumoniae, which remain poorly defined. Using the representative K. pneumoniae AJ218 strain, we showed that the P-type ATPase, ZntA, which is upregulated in response to cellular zinc stress, was the primary zinc efflux pathway. Deletion of rendered K. pneumoniae AJ218 highly susceptible to exogenous zinc stress and manifested as an impaired growth phenotype and increased cellular accumulation of the metal. Loss of also increased sensitivity to cadmium stress, indicating a role for this efflux pathway in cadmium resistance. Disruption of zinc homeostasis in the K. pneumoniae AJ218 Δ strain also impacted manganese and iron homeostasis and was associated with increased production of biofilm. Collectively, this work showed the critical role of ZntA in K. pneumoniae zinc tolerance and provided a foundation for further studies on zinc homeostasis and the future development of novel antimicrobials to target this pathway. Klebsiella pneumoniae is a leading cause of healthcare-associated infections, including pneumonia, urinary tract infections, and sepsis. Treatment of K. pneumoniae infections is becoming increasingly challenging due to high levels of antibiotic resistance and the rising prevalence of carbapenem-resistant, extended-spectrum β-lactamases producing strains. Zinc is essential to the colonization and infection by many bacterial pathogens but toxic in excess. This work described the first dissection of the pathways associated with resisting extracellular zinc stress in K. pneumoniae. This study revealed that the P-type ATPase ZntA was highly upregulated in response to exogenous zinc stress and played a major role in maintaining bacterial metal homeostasis. Knowledge of how this major bacterial pathogen resists zinc stress provided a foundation for antimicrobial development studies to target and abrogate their essential function.
肺炎克雷伯菌是一种机会性革兰氏阴性病原体，是导致与医疗保健相关的感染的主要原因，包括肺炎、尿路感染和败血症。肺炎克雷伯菌定植和感染的关键是获取营养物质，如过渡金属离子锌。锌在所有生物体的蛋白质组中具有至关重要的结构和催化作用。然而，过量的锌有可能通过失调其他过渡元素的内稳态、破坏酶促过程以及扰乱金属蛋白辅因子的获取来介导显著的毒性。在这里，我们试图阐明肺炎克雷伯菌的锌解毒机制，目前对此知之甚少。使用代表性的肺炎克雷伯菌 AJ218 菌株，我们表明 P 型 ATP 酶 ZntA 是主要的锌外排途径，该酶在细胞锌应激下上调。 缺失 使肺炎克雷伯菌 AJ218 对外源性锌应激高度敏感，并表现出生长表型受损和金属细胞积累增加。 的缺失也增加了对镉应激的敏感性，表明该外排途径在镉抗性中起作用。肺炎克雷伯菌 AJ218Δ 株中锌动态平衡的破坏也影响了锰和铁动态平衡，并与生物膜产量增加有关。总的来说，这项工作表明 ZntA 在肺炎克雷伯菌锌耐受中的关键作用，并为进一步研究锌动态平衡和未来开发针对该途径的新型抗菌药物提供了基础。
