Proteomic profiles of BpsI-mediated Burkholderia pseudomallei and its roles on antibiotic susceptibility, biofilm formation, stress response and pathogenesis mechanism

Burkholderia pseudomallei is the causative agent of a fatal disease, melioidosis. However, the mechanisms of pathogenesis and genes involved in its survival are not completely understood. In the current study, role of BpsI-mediated quorum sensing (QS) system was investigated. We constructed a stable markerless bpsI knockout mutants (ΔbpsI1, ΔbpsI2, and ΔbpsI3) strain using a pEXKm5-based allele replacement method to investigate the impact of BpsI on B. pseudomallei strain K96243. Proteomic analysis revealed significant alterations of protein expression between the wild type (WT) and ΔbpsI mutant strains, showing 40, 202, and 5 genes is controlled by BpsI1, BpsI2 and BpsI3, respectively. Interestingly, Deletion of bpsI genes affected B. pseudomallei's stress response, biofilm formation, antibiotic susceptibility, and pathogenicity in a gene-specific manner. Deletion of bpsI1 or bpsI2 caused reduced heat tolerance, while deletion of bpsI1 or bpsI2 or bpsI3 caused reduced oxidative stress. Deletion of bpsI1 or bpsI3 led to diminished biofilm formation. For antibiotic susceptibility, deletion of bpsI1, bpsI2 or bpsI3 displayed increased susceptibility to imipenem and ceftazidime. Deletion of bpsI1 or bpsI3 showed increased susceptibility to amoxicillin/clavulonate, while deletion of bpsI2 or bpsI3 was more susceptibility to meropenem. Nevertheless, only deletion of bpsI1 exhibited lower MICs for chloramphenicol. Moreover, deletion bpsI1 or bpsI2 resulted in decreased pathogenicity during human skin fibroblast infection, associating with weakened virulence in the Galleria mellonella and Caenorhabditis elegans models. However, the deletion of bpsI3 did not affect a virulence in the Galleria mellonella and Caenorhabditis elegans models. Taken together, our findings indicate that the QS system, mediated by BpsI1, BpsI2, and BpsI3, may play a complex and important role in both the environmental adaptation and pathogenicity of B. pseudomallei.