Impact of the pentose phosphate pathway on metabolism and pathogenesis of Staphylococcus aureus

Staphylococcus aureus is an important pathogen that leads to significant disease through multiple routes of infection. We recently published a transposon sequencing (Tn-seq) screen in a mouse acute pneumonia model and identified a hypothetical gene (SAUSA300_1902, pgl) with similarity to a lactonase of Escherichia coli involved in the pentose phosphate pathway (PPP) that was conditionally essential. Limited studies have investigated the role of the PPP in physiology and pathogenesis of S. aureus. We show here that mutation of pgl significantly impacts ATP levels and respiration. RNA-seq analysis of the pgl mutant and parent strains identified compensatory changes in gene expression for glucose and gluconate as well as reductions in the pyrimidine biosynthesis locus. These differences were also evident through unbiased metabolomics studies and 13C labeling experiments that showed mutation of pgl led to reductions in pyrimidine metabolism including decreases in ribose-5P, UMP and GMP. These nucleotide reductions impacted the amount of extracellular DNA in biofilms and reduced biofilm formation. Mutation also limited the capacity of the strain to resist oxidant damage induced by hydrogen peroxide and paraquat and subsequent intracellular survival inside macrophages. Changes in wall teichoic acid impacted susceptibility to hydrogen peroxide. We demonstrated the importance of these changes on virulence in three different models of infection, covering respiratory, skin and septicemia, demonstrating the need for proper PPP function in all models. This work demonstrates the multifaceted role metabolism can play in multiple aspects of S. aureus pathogenesis. Author summaryStaphylococcus aureus is an important cause of a variety of diseases. Due to its propensity to be resistant to antibiotics and the absence of a vaccine, studies to understand its fundamental physiology are important identify potential new avenues for treatment. In this study we investigated the role of one aspect of S. aureus metabolism: the pentose phosphate pathway. We demonstrated that decreased carbon flux through this pathway not only led to disruptions in the ability of the bacteria to generate energy but also influence multiple facets of its ability to cause infection. We confirmed the impact of these changes in multiple models of infection to reflect the varied diseases S. aureus can cause. This work demonstrated that metabolism does not merely impact the energy requirements of bacteria but can impact important functions that play direct roles in the organism's ability to cause disease.