Poster Presentation BacPath 2024

The role of FruA in Streptococcus pneumoniae carbohydrate metabolism. (#77)

Nicholas T Maczuga 1 , Kimberley McLean 1 , James Paton 1 , Claudia Trappetti 1 2 , Erin Brazel 1
  1. Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
  2. Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy

The Gram-positive bacterial pathogen Streptococcus pneumoniae is responsible for more than one million deaths each year. Understanding how pneumococci interact with the host environment during an infection is an important step in the identification of new strategies for combating disease. Previous work demonstrated that the pneumococcal FruA phosphoenolpyruvate (PEP):carbohydrate phosphotransferase (PTS) protein contributes to fructose metabolism. In the present study, we evaluated the contribution of this protein to carbohydrate metabolism by assessing the growth kinetics of a fruA isogenic deletion (∆fruA) and single amino acid substitution variant strains. The regulation of this system was assessed by measurements of fruA expression in strains harbouring deletions of the lacR1 or ccpA gene, to explore their contribution to controlling expression of this pathway. We further probed the role of this gene in vivo by exploring the pathogenesis the ∆fruA strain in a mouse model of infection. Mice were intranasally challenged with the wild-type or ∆fruA strain and the bacterial numbers in various sites were enumerated at 24 hours post-challenge. Mice infected with ∆fruA displayed a higher bacterial burden in the ears and brain compared with mice challenged with the parental strain. While membrane proteins are notoriously challenging to biochemically characterise, we successfully heterologously expressed and purified FruA, providing the foundation for future biochemical and structural studies. Overall, this study validated the contribution of FruA to fructose metabolism and identified putative residues involved in FruA function. This work also highlighted potential pleiotropic impacts of dysregulated carbohydrate regulation and suggest that the fructose metabolic pathway may influence pneumococcal tissue tropism. Taken together, these data support the role of FruA in S. pneumoniae carbohydrate metabolism and provide a basis for further structural and functional analyses of FruA.