嗜水气单胞菌ntrC调控的生理功能及其机制研究

Physiological function and mechanism mediated by ntrC in Aeromonas hydrophila

摘要:

[目的] NtrC是一种与DNA结合的转录调控因子，在激活氮同化基因的转录和维持氮源供应中具有重要作用，本研究拟探究其对嗜水气单胞菌生理功能的影响及其作用机理。[方法] 本研究采用同源重组方法构建了嗜水气单胞菌ATCC 7966 ntrC的缺失株，并以野生株为对照，对缺失株的生理表型进行测定和分析，利用定量蛋白质组学技术比较野生株和ntrC缺失株的蛋白表达差异。[结果] 发现敲除ntrC基因后，嗜水气单胞菌在缺氮、渗透压、重金属离子、氧化以及不同抗生素胁迫下的耐受性都发生显著变化，且这些表型在其补救菌株中均能得到恢复。定量蛋白质组学分析发现，野生株和ntrC缺失株的差异表达蛋白可能参与氨基酸生物合成、抗坏血酸和醛糖酸盐等代谢通路的调控。[结论] 本研究阐明了ntrC在嗜水气单胞菌中的重要作用及其对细菌生物学功能的影响，探讨了ntrC直接或间接调控的蛋白与生理表型之间的联系，研究结果可为未来水产致病菌的防治提供理论支持。

Abstract:

[Objective] NtrC is a DNA-binding transcriptional regulator which plays an important role in activating the transcription of nitrogen assimilation genes and maintaining nitrogen supply. The objectives of this study were to explore its physiological function and mechanism in Aeromonas hydrophila.[Methods] In this study, the homologous recombination method was used to construct the ntrC deletion strain of Aeromonas hydrophila, and the physiological phenotype of the deletion strain was measured and analyzed with the wild strain as the control. A data independent acquisition-based quantitative proteomics method was performed to compare the protein expression differences between the wild-type and ntrC deletion strains.[Results] After the ntrC gene was knocked out, the tolerance of Aeromonas hydrophila to nitrogen deficiency, osmotic pressure, heavy metal ions, oxidation and different antibiotic stress was significantly changed, and these phenotypes could be recovered in its rescued strains. Quantitative proteomics was used to compare the protein expression between the WT and the ntrC deletion strain. Results showed that ntrC may be involved in the regulation of biosynthesis of amino acids, ascorbate and aldose metabolism pathways. [Conclusion] This study elucidated the important role of NtrC in Aeromonas hydrophila and its impact on the biological function of the bacteria. Moreover, the relationship between the proteins directly or indirectly regulated by NtrC and the physiological phenotype was discussed, the results provide valuable information for the prevention and control of aquatic pathogens in the future.