Virtual Poster 21st Lancefield International Symposium for Streptococci and Streptococcal Diseases 2022

The non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase GapN is a potential new drug target in Streptococcus pyogenes (#416)

Philip Eisenberg 1 , Leon Albert 2 , Jonathan Teuffel 3 , Eric Zitzow 1 , Claudia Michaelis 1 , Jane Jarick 1 , Clemens Sehlke 1 , Lisa Große 1 , Nicole Bader 2 , Ariane Nunes-Alves 3 4 , Bernd Kreikemeyer 1 , Hermann Schindelin 2 , Rebecca C. Wade 3 4 5 , Tomas Fiedler 1
  1. Institute of Medical Microbiology, Virology, and Hygiene, Rostock University Medical Centre, Rostock, Germany
  2. Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
  3. Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies, Heidelberg, Germany
  4. Center for Molecular Biology (ZMBH), DKFZ-ZMBH Alliance, Heidelberg University, Heidelberg, Germany
  5. Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany

Background: Although generally susceptible to penicillin, lately increased penicillin tolerance is observed in clinical S. pyogenes (GAS) strains. Furthermore, intracellular persistence of GAS leads to penicillin treatment failure and is associated with macrolide resistance. Hence, new antimicrobials ideally targeting specifically GAS without interfering with the commensal flora are needed. In this study we aimed to establish the non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase GapN as a drug target for GAS.

Methods: In GAS M49 strain 591 and seven macrolide resistant GAS strains, the effect of a  gapN gene knock down using antisense peptide nucleic acids (asPNA) on bacterial survival in vitro was investigated. The crystal structure of GapN was solved and a structural model predicting binding affinities in the substrate binding pocket was established. Potential competitive inhibitors predicted by in silico docking were tested in enzymatic assays.

Results: The knock-down of gapN by asPNA significantly reduced viable counts of all GAS strains tested. Since GAS lacks the oxidative part of the pentose phosphate pathway, GapN appears to be the major source of NADPH. Accordingly, other streptococci that carry a complete pentose phosphate pathway, e.g. S. cristatus, are not prone to asPNA-based gapN knock-down. The computationally predicted competitive inhibition of the enzyme by erythrose 4-phosphate was consistent with the results of our experimental data, indicating that our model can be used for in silico screening for potential specific inhibitors.

Conclusion: GapN is a potential target for antimicrobial substances that selectively kill GAS and other streptococci that lack the oxidative part of the pentose phosphate pathway.