mBio (Dec 2022)
Metabolic Mechanism and Physiological Role of Glycerol 3-Phosphate in Pseudomonas aeruginosa PAO1
Abstract
ABSTRACT Pseudomonas aeruginosa is an important opportunistic pathogen that is lethal to cystic fibrosis (CF) patients. Glycerol generated during the degradation of phosphatidylcholine, the major lung surfactant in CF patients, could be utilized by P. aeruginosa. Previous studies have indicated that metabolism of glycerol by this bacterium contributes to its adaptation to and persistence in the CF lung environment. Here, we investigated the metabolic mechanisms of glycerol and its important metabolic intermediate glycerol 3-phosphate (G3P) in P. aeruginosa PAO1. We found that G3P homeostasis plays an important role in the growth and virulence factor production of P. aeruginosa PAO1. The G3P accumulation caused by the mutation of G3P dehydrogenase (GlpD) and exogenous glycerol led to impaired growth and reductions in pyocyanin synthesis, motilities, tolerance to oxidative stress, and resistance to kanamycin. Transcriptomic analysis indicates that the growth retardation caused by G3P stress is associated with reduced glycolysis and adenosine triphosphate (ATP) generation. Furthermore, two haloacid dehalogenase-like phosphatases (PA0562 and PA3172) that play roles in the dephosphorylation of G3P in strain PAO1 were identified, and their enzymatic properties were characterized. Our findings reveal the importance of G3P homeostasis and indicate that GlpD, the key enzyme for G3P catabolism, is a potential therapeutic target for the prevention and treatment of infections by this pathogen. IMPORTANCE In view of the intrinsic resistance of Pseudomonas aeruginosa to antibiotics and its potential to acquire resistance to current antibiotics, there is an urgent need to develop novel therapeutic options for the treatment of infections caused by this bacterium. Bacterial metabolic pathways have recently become a focus of interest as potential targets for the development of new antibiotics. In this study, we describe the mechanism of glycerol utilization in P. aeruginosa PAO1, which is an available carbon source in the lung environment. Our results reveal that the homeostasis of glycerol 3-phosphate (G3P), a pivotal intermediate in glycerol catabolism, is important for the growth and virulence factor production of P. aeruginosa PAO1. The mutation of G3P dehydrogenase (GlpD) and the addition of glycerol were found to reduce the tolerance of P. aeruginosa PAO1 to oxidative stress and to kanamycin. The findings highlight the importance of G3P homeostasis and suggest that GlpD is a potential drug target for the treatment of P. aeruginosa infections.
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