The Relationship Between YihE Kinase-Mediated Protection And ROS In Escherichia Coli

Nowadays,the emergence of pathogens that are resistant to multiple antibiotics has become a global public health threat.Studies show that the bacterial programmed cell death pathways have the potential to become targets of new antibiotics.In previous studies,YihE protein kinase,a central regulator of programmed cell death in bacteria,is shown to be able to protect bacteria during drug treatment.Meanwhile,ROS is shown to be involved in the bactericidal action of antimicrobial agents,and the intracellular accumulation of hydroxyl radicals is one of the main mechanisms of drug sterilization in bacteria.However,it is still unclear whether the protective effect of YihE on bacteria is related to the production and accumulation of ROS.In this work,the relationship between YihE-mediated protection and ROS in Escherichia coli was studied.Analyses of the sensitivity of the yihE and cpx mutants to nalidixic acid showed that YihE and the Cpx two-component system could protect bacteria from nalidixic acid-mediated cell death,and the Cpx system might mainly work through YihE to protect bacteria.Besides,the protective effect of YihE on bacteria against H2O2 was also analyzed,and the response of to H2O2 was found to be related to the Cpx system.The Cpx system might mainly work through YihE in its response to H2O2.To further understand the relationship between the function of YihE and ROS,the protection of YihE on bacteria in the presence of ascorbic acid and reduced glutathione was examined.The results showed that ascorbic acid and glutathione could protect the cells from the bactericidal effect of nalidixic acid,which further indicated that the protection provided by YihE was related to ROS.In addition,it was found that ascorbic acid and glutathione might work in the same pathway to exert their protection against nalidixic acid.At the same time.the expression of soxR,oxyR,ahpC,katG and yaaA genes in the wild-type strain and the yihE mutant was measured.Compared to that in the wild type strain,the expression of these 5 genes in the yihE mutant increased,indicating that the action of YihE may be involved in the changes in the levels of cellular ROS.The expression of all these genes in wild type strain increased when treated with nalidixic acid,while their expression,except for katG,decreased in the yihE mutant,which implied that the bacterial responses to drug-mediated oxidative stress were attenuated in the absence of YihE.In summary,the results revealed that YihE-mediated protection was related to ROS,which might involve the accumulation of superoxide radicals,hydrogen peroxide,and hydroxyl radicals.This study would help us to further understand the interaction between bacteria and external environment,as well as their survival mechanism in the presence of antimicrobial agents.It would also provide a new perspective on the mechanism of drug action and bacterial resistance,and lay the foundation for future development of new drugs against bacterial self-protection system.