Cell Pathway And Regulation Mechanisms Of Protein Kinase YihE

The increasing emergence of multi-drug resistant bacteria has posed a serious threat to human health.New strategies are badly need to contain the multi-drug resistance,in addition to developing novel antimicrobial agents.Therefore,in recent years,people began to pay attention to the molecular mechanism of bacterial resistance,hoping to find a new breakthrough point.Our previous studies have shown that YihE kinase is a key regulator of the programmed cell death pathway in Escherichia coli,which could protect bacteria when treated with antibiotics.However,the cellular pathway of YihE kinase and its regulation mechanism are still unclear.In order to understand the specific regulatory mechanism of YihE,in the present work,we first screened for genes whose expression are affected by a yihE mutation by using transcriptome sequencing.By analyzing the function of related genes,it was found that the pathways affected by the yihE mutation mainly include nitrate reduction pathway,ED pathway(pentose phosphate pathway),and glucose metabolism and transport related pathways.Drug susceptibility test showed that genes narK,gntK,fruK,gntT,edd,narG,and ptsG in these pathways could protect bacteria from nalidixic acid-mediated killing.Studies on the nitrate reductase NarG,a key enzyme in the nitrate reduction pathway,showed that it provided the proton driving force for bacterial drug efflux pumps to protect cells.At the same time,elevated levels of NO in the AyihE mutant indicated that the protective effect of YihE on cells might also related to nitrative stress.Under drug treatment,the intracellular level of free iron and ROS increased in the ?yihE mutant when compared to that in the wild-type strain,indicating that YihE might protect cells by decreasing the intracellular level of reactive oxygen species(ROS)through affecting the level of free iron in the cells.Therefore,we propose the cellular pathway and the regulation mechanism of YihE:1)YihE regulates intracellular nitrate metabolism by phosphorylating its target protein,so that the level of intracellular RNS is not too high to affect cel]survival;2)YihE may phosphorylate DnaK,and DnaK negatively regulates the ED pathway to reduce the toxic effects of ROS on bacteria and ultimately avoid cell death.This study revealed part of the cellular pathway of YihE and its regulatory mechanism,which would provide the basis for increasing the bactericidal efficacy of existing drugs through developing antimicrobial agents that counter the bacterial self-protection mechanism.