Lin Tien-Huang, Wang Chen-Yu, Wu Chien-Chen, Lin Ching-Ting
Department of Urology, Taichung Tzu Chi Hospital, The Buddhist Tzu Chi Medical Foundation, Taichung, Taiwan; School of Post-Baccalaureate Chinese Medicine, Tzu Chi University, Hualien, Taiwan.
Graduate Institute of Chinese Medicine, School of Chinese Medicine, China Medical University, Taichung, Taiwan; Department of Chinese Medicine, China Medical University Hsinchu Hospital, Hsinchu, Taiwan.
J Microbiol Immunol Infect. 2025 Feb;58(1):48-55. doi: 10.1016/j.jmii.2024.10.002. Epub 2024 Oct 24.
Klebsiella pneumoniae is a Gram-negative bacterium that can cause infections, especially in individuals with diabetes. Recently, more hypervirulent strains have emerged, posing a threat even to healthy individuals. Understanding how K. pneumoniae regulates its virulence factors is crucial. Acetyl-phosphate (AcP) is essential for bacterial metabolism and can affect virulence factor expression. However, the role of the Pta-AckA pathway, which regulates AcP levels, in K. pneumoniae pathogenesis remains unclear.
Deletion mutants lacking the pta and ackA, involved in AcP production and hydrolysis, were generated in K. pneumoniae CG43S3. Their effects on AcP levels, the patterns of global acetylated protein, capsular polysaccharide (CPS) amount, serum resistance, type 3 fimbriae expression, biofilm formation, and virulence in G. mellonella larva were assessed.
Deletion of ackA in K. pneumoniae CG43S3 led to AcP accumulation, while pta deletion abolished AcP synthesis when grown in TB7+1 % glucose. This pathway influenced global protein acetylation, with pta deletion decreasing acetylation and ackA deletion increasing it. Additionally, pta deletion decreased the CPS amount, serum resistance, and type 3 fimbriae expression, while ackA deletion increased these factors. Furthermore, deleting pta and ackA attenuated the infected larva's virulence and death rate.
Our findings highlight the critical role of the Pta-AckA pathway in K. pneumoniae pathogenesis. This pathway regulates AcP levels, global protein acetylation, CPS production, serum resistance, and type 3 fimbriae expression, ultimately impacting virulence. The information provides insights into potential therapeutic targets for combating K. pneumoniae infection.
肺炎克雷伯菌是一种革兰氏阴性菌，可引发感染，尤其是在糖尿病患者中。近来，出现了更多高毒力菌株，甚至对健康个体也构成威胁。了解肺炎克雷伯菌如何调节其毒力因子至关重要。乙酰磷酸（AcP）对细菌代谢必不可少，且会影响毒力因子表达。然而，调节AcP水平的Pta - AckA途径在肺炎克雷伯菌致病机制中的作用仍不清楚。
在肺炎克雷伯菌CG43S3中构建了缺乏参与AcP产生和水解的pta和ackA的缺失突变体。评估了它们对AcP水平、全局乙酰化蛋白模式、荚膜多糖（CPS）量、血清抗性、3型菌毛表达、生物膜形成以及在米氏蜜蜂幼虫中的毒力的影响。
肺炎克雷伯菌CG43S3中ackA的缺失导致AcP积累，而在TB7 + 1%葡萄糖中生长时pta的缺失消除了AcP合成。该途径影响全局蛋白乙酰化，pta缺失使乙酰化减少，ackA缺失使乙酰化增加。此外，pta缺失降低了CPS量、血清抗性和3型菌毛表达，而ackA缺失则增加了这些因素。此外，删除pta和ackA减弱了感染幼虫的毒力和死亡率。
我们的研究结果突出了Pta - AckA途径在肺炎克雷伯菌致病机制中的关键作用。该途径调节AcP水平、全局蛋白乙酰化、CPS产生、血清抗性和3型菌毛表达，最终影响毒力。这些信息为对抗肺炎克雷伯菌感染的潜在治疗靶点提供了见解。
