Molecular Mechanism Of PrtR Regulating Acute And Chronic Infection In Pseudomonas Aeruginosa

Pseudomonas aeruginosa is a common clinical opportunistic pathogen that causes acute and chronic infections.The survival state of bacteria motile or sessile directly affects the conversion of bacterial acute and chronic infection.Chronic infection is caused by the living state of bacteria and the biofilm.Extracellular polysaccharides are one of the key components of biofilms.For further researching the regulation mechanism of extracellular polysaccharides during bacterial lifestyle transformation,the pyocin regulator PrtR was obtained by the DNA affinity chromatography using the psl promoter,which directly binds to the psl polysaccharide synthesis gene cluster promoter.The prt R mutant shows a different phenotype than wild-type PAO1,such as increased biofilm,colony wrinkle aggregation,and increased intracellular c-di-GMP levels.To further systematically study the function of PrtR,we obtained PrtR-regulated genes at the genome-wide level by RNA-seq high-throughput sequencing.RNA-seq data analysis shows that 735 genes regulated by PrtR accounts for approximately14% of the whole genome of P.aeruginosa,including genes for T3 SS,T6SS,and pyocin synthesis.Importantly,the data shows that prt R significantly negatively regulats the activity of the biguanylate cyclase SiaD.PrtR protein was directly interacted with SiaD protein by bacterial two-hybrid and pull-down experiments.The enzyme activity assay demonstrats that the interaction between PrtR and SiaD protein affects intracellular c-di-GMP levels.SiaD is involved in the regulation of intracellular c-di-GMP levels and biofilm formation in the mutant prt R.In addition,PrtR regulates the expression of the type III secretion system(T3SS)and the type VI secretion system(T6SS)by directly acting on the promoter region of lads to regulate the activity of the Lad S and its underlying Gac/Rsm system.In conclusion,This study identifies a novel c-di-GMP regulator,the results demonstrate that PrtR not only binds to the lad S promoter but also affects downstream Lad S/Gac/Rsm,while the PrtR protein interacts directly with the SiaD protein to affect c-di-GMP levels.This study reveals a novel mechanism by which PrtR mediates the P.aeruginosa lifestyle transition by regulating c-di-GMP signaling.This research provides a theoretical basis for us to better understand the virulence regulation network and clinical treatment of P.aeruginosa.