Department of Science, University Roma Tre, Rome, Italy.
Department of Molecular and Cellular Biology "Charles Darwin", University Roma Sapienza, Rome, Italy.
Sci Rep. 2022 Jun 21;12(1):10404. doi: 10.1038/s41598-022-14635-7.
In Gram-negative pathogens, the stringent response regulator DksA controls the expression of hundreds of genes, including virulence-related genes. Interestingly, Pseudomonas aeruginosa has two functional DksA paralogs: DksA1 is constitutively expressed and has a zinc-finger motif, while DksA2 is expressed only under zinc starvation conditions and does not contain zinc. DksA1 stimulates the production of virulence factors in vitro and is required for full pathogenicity in vivo. DksA2 can replace these DksA1 functions. Here, the role of dksA paralogs in P. aeruginosa tolerance to HO-induced oxidative stress has been investigated. The P. aeruginosa dksA1 dksA2 mutant showed impaired HO tolerance in planktonic and biofilm-growing cultures and increased susceptibility to macrophages-mediated killing compared to the wild type. Complementation with either dksA1 or dksA2 genes restored the wild type phenotypes. The DksA-dependent tolerance to oxidative stress involves, at least in part, the positive transcriptional control of both katA and katE catalase-encoding genes. These data support the hypothesis that DksA1 and DksA2 are eco-paralogs with indistinguishable function but optimal activity under different environmental conditions, and highlight their mutual contribution to P. aeruginosa virulence.
在革兰氏阴性病原体中，严格反应调节剂 DksA 控制着数百个基因的表达，包括与毒力相关的基因。有趣的是，铜绿假单胞菌有两个功能上的 DksA 同源物：DksA1 持续表达并具有锌指基序，而 DksA2 仅在缺锌条件下表达且不含锌。DksA1 刺激体外毒力因子的产生，是体内完全致病性所必需的。DksA2 可以替代这些 DksA1 功能。在这里，研究了 dksA 同源物在铜绿假单胞菌对 HO 诱导的氧化应激的耐受性中的作用。与野生型相比，铜绿假单胞菌 dksA1 dksA2 突变体在浮游和生物膜生长培养物中对 HO 的耐受性受损，并且对巨噬细胞介导的杀伤的敏感性增加。用 dksA1 或 dksA2 基因进行互补恢复了野生型表型。DksA 依赖的对氧化应激的耐受性至少部分涉及 katA 和 katE 过氧化氢酶编码基因的正转录控制。这些数据支持了这样一种假设，即 DksA1 和 DksA2 是生态同源物，具有相同的功能，但在不同的环境条件下具有最佳的活性，并突出了它们对铜绿假单胞菌毒力的相互贡献。
