大肠杆菌转录调控因子oxyR与抗氧化基因ahpCF、katEG的协同作用

Synergistic effect of transcription factor oxyR with antioxidant genes ahpCF and katEG in Escherichia coli

中文关键词:  抗氧化  过氧化氢  大肠杆菌  生长繁殖

英文关键词:catalase  hydrogen peroxide  Escherichia coli  growth and proliferation

中文摘要:

      目的 探讨大肠杆菌转录调控因子oxyR与抗氧化基因ahpCF、katEG在调控内源过氧化氢(H2O2)水平及生长繁殖中的作用。方法 荧光法检测大肠杆菌内源H2O2, 采用以氯化铈做特异染色剂的透射电子显微镜法和AR做染料的荧光分光光度法检测内源H2O2的数量变化。结果 突变体菌株JI374中ahpCF基因的缺失导致内源H2O2积累减少, 其生长速度显著提高。与此相反的是, katEG基因缺失的突变体菌株JI372和ahpCF、oxyR基因双突变菌株LC74中, 内源H2O2水平上升, 抑制了细菌的生长速率。结论 oxyR调控下的抗氧化体系相关基因不仅能够调控细菌内源H2O2水平, ahpCF、katEG与转录调控因子oxyR之间具有协同作用, 共同调控细菌的生长代谢与繁殖。同时, 在ahp基因缺失条件下, kat基因起主导作用; 在oxyR、ahpCF、katEG基因的协同作用中, oxyR应起决定性的作用。

英文摘要:

      Objective To explore the effect of transcription factor oxyR with antioxidant genes ahpCF and katEG in Escherichia coli on the endogenous hydrogen peroxide accumulation and its growth and proliferation. Methods The endogenous H2O2 in Escherichia coli was detected by fluorescence method. The quantity of endogenous H2O2 was detected by transmission electron microscopy with cerium chloride as the specific stain and fluorescence spectrophotometry with AR as the dye. Results The mutation of ahpCF gene caused the decrease of endogenous H2O2 accumulation which led to growth corresponding accelerated in mutant strain JI374. However, in the mutant strain JI372 with the katG gene deletion and the mutant strain LC74 with ahpCF, oxyR gene, the level of H2O2 accumulation increased, and exhibited the growth rate of bacteria. Conclusion Gene expression of antioxidant system can regulate the level of endogenous hydrogen peroxide in bacteria, and ahpCF, katEG and the transcription factor oxyR may have synergy in affecting the overall growth and proliferation of the strains. At the same time, under lacking ahp gene conditions, kat gene plays a leading role and oxyR gene plays a decisive role in coordinating role of oxyR, ahp, kat genes.