Elucidating the Functions of fabF1 and fabF2 in Pseudomonas aeruginosa: Implications for Fatty Acid Metabolism and Pathogenicity

Background Pseudomonas aeruginosa is an opportunistic pathogen associated with severe infections in immunocompromised individuals, including burn patients and those with cystic fibrosis. β-ketoacyl-ACP synthases are a class of key enzymes in bacterial fatty acid metabolism, with functions that directly impact basic cellular metabolism and pathogenicity. Two types of long-chain β-ketoacyl-ACP synthases have been identified: FabB and FabF. This study investigates the roles of fabF 1 and fabF 2 genes in the fatty acid biosynthesis and virulence of P. aeruginosa PAO1. Results Complementation assays in Escherichia coli demonstrated that fabF2 can substitute for the E. coli FabB enzyme, while FabF1 exhibits FabF-like activity. In P. aeruginosa PAO1, deletion of fabF1 significantly decreased cis -vaccenic acid levels and increased palmitoleic acid, whereas deletion of fabF2 had no effect. The double mutant showed a marked reduction in cis -vaccenic acid. Virulence assays revealed that the Δ fabF1 strain exhibited a 63% reduction in rhamnolipid production, while the Δ fabF2 strain showed a 45% reduction. The double mutant retained only 28% of wild-type rhamnolipid levels. Additionally, pyoverdine secretion was substantially reduced in the double mutant, and both LasA protease activity and pyocyanin production were compromised. Motility assays indicated reduced swimming, twitching, and swarming abilities in the mutants. Conclusions These findings underscore the crucial roles of fabF 1 and fabF 2 in the fatty acid biosynthesis, virulence factor production, and motility of P. aeruginosa , providing insights into potential targets for antimicrobial development.