Regulation Of Virulence By Heat Shock Protein Gene DnaJ In Pseudomonas Aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen which can cause acute and chronic infections.Its pathogenecity is often realized through a number of virulence factors.Therefore,to study the regulation of virulence is the key to understand the pathogenic mechanism of pathogens.With a focus on a PA4760 transposable mutant(dnaJ-Tm)previously obtained in our laboratory,this study aimed to reveal the effects of dnaJ on Pseudomonas aeruginosa virulence and the underlying mechanisms.Pseudomonas aeruginosa DnaJ is a heat shock protein.DnaJ and DnaK together constitute a molecular chaperone system,which is involved in the folding and degradation of new synthetic proteins to maintain protein homeostasis in cells.Relevant studies have shown that heat shock protein DnaJ is extremely important for growth.The growth experiment results showed that the dnaJ mutation did not show growth defects in pseudomonas aeruginosa.Meanwhile,it was also found that the dnaJ mutation did not affect the growth of pseudomonas aeruginosa under adverse conditions(high temperature and low temperature).In addition,studies have shown that the dnaJ mutation can cause significant changes the virulence in other bacteria.In this study,the main virulence of dnaJ-Tm,including pyocyanin,elastase and extracellular DNA(eDNA),were determined by crystal violet staining and motility experiment.The results showed that the virulence of pyocyanin,biofilm,motility elastase and eDNA decreased significantly after dnaJ mutation,but the synthesis of rhamnolipid increased significantly.At the same time,the pathogenicity of dnaJ mutation was significantly reduced through drosophila infection experiment.This indicates that the gene dnaJ plays an important role in the virulence of pseudomonas aeruginosa.In addition,the specific mechanism of virulence regulation by dnaJ was studied through detecting gene expression and exogenous addition of eDNA and pyocyanin.The results showed that dnaJ may affect the synthesis of pyocyanin by regulating the expression of phz genes(phz M,phz S,phz A1 and phz A2),further affect the level of eDNA,and finally affect adhesion and biofilm.In addition,it was found that dnaJ may regulate the expression of rsm A through rpo S.In summary,the heat shock protein gene dnaJ can regulate the virulence such as pyocyanin,biofilm and motility in pseudomonas aeruginosa.In addition,dnaJ can regulate the expression of type III secretory gene rsm A.Therefore,the decrease of pathogenicity caused by heat shock protein gene dnaJ of pseudomonas aeruginosa may be a result of comprehensive results.