Investigation Of The Pathogenicity Of The Gene PA4429-31 In Pseudomonas Aeruginosa

In the past decade,many clinical pathogens exhibit naturally low susceptibility to antibiotics and acquires resistance more easily due to long-term exposure to drugs or antibiotics,threatening people’s health.Pseudomonas aeruginosa is an opportunistic pathogen which were known to be ubiquitous in a variety of environments and can lead to acquired infections in hospitals.However,the treatment of P.aeruginosa has become more difficult due to the environmental adaptation and the extensive drug resistance of P.aeruginosa itself.Therefore,understanding and controlling the infection of P.aeruginosa is an important topic in current clinical research.The respiratory chain is essential for bacterial growth and metabolic processes and is involved in bacterial resistance and pathogenicity.The respiratory chain can be used as a new target for the treatment of P.aeruginosa infections.Previously,it has found that PAO1(Δ4429),PAO1(Δ4430),PAO1(Δ4431)have increased resistance to aminoglycoside antibiotics.According to the KEGG pathway,the genes PA4429,PA4430 and PA4431 probable encode cytochrome c1,cytochrome b and iron-sulfur protein respectively,and the three genes together constitute the cytochrome bc1 complex.In this study,bioinformatics alignment and phylogenetic tree construction were further proved that genes PA4429,PA4430 and PA4431 may encode cytochrome c1,cytochrome b and iron-sulfur protein.Medium color of PAO1(Δ4429),PAO1(Δ4430),PAO1(Δ4431)were lighter compared to wild type PAO1,genes PA4429,PA4430 and PA4431 were suspect to may affect the production of pyocyanin or the toxicity of P.aeruginosa.It was found that inactivation of genes PA4429,PA4430,PA4430 and PA4429-31 can result in the production of virulence factors of P.aeruginosa such as pyocyanin,exopolysaccharide,elastase and rhamnolipid by constructing deletion mutant PAO1(Δ4429-31)and complementing the genes PA4427-31 to PAO1(Δ4429),PAO1(Δ4430),PAO1(Δ4431)and PAO1(Δ4429-31),andexamining the pyocyanin production and phenotype of other virulence factors of these mutants and complements.The relevant phenotype of PAO1(Δ4429),PAO1(Δ4430),PAO1(Δ4431)and PAO1(Δ4429-31)also change,such as the reduction of bacterial exercise capacity.The literature indicates that the virulence factors produced by P.aeruginosa can be regulated by the quorum sensing system.In this study,the relationship between the gene PA4429-31 and QS was studied by using the operon of the luciferase gene as a luminescent reporter.It was found that inactivation of PA4429-31 caused a decrease in the expression of genes involved in the quorum sensing system,indicating that the gene PA4429-31 can have a positive impact on QS.This study found that the gene PA4429-31 involved in encoding of the respiratory chain can lead to a decrease in the production of virulence factors in P.aeruginosa.In addition,it has found that the gene PA4429-31 can affect QS.These results lay a foundation for subsequent understanding of the pathogenic mechanisms in P.aeruginosa and provide a new therapeutic target.