Vitamin B6 inhibits activity of Helicobacter pylori adenylosuccinate synthetase and growth of reference and clinical, antibiotic-resistant H. pylori strains

J Enzyme Inhib Med Chem. 2024 Dec;39(1):2372734. doi: 10.1080/14756366.2024.2372734. Epub 2024 Aug 16.

Abstract

The current therapies against gastric pathogen Helicobacter pylori are ineffective in over 20% of patients. Enzymes belonging to the purine salvage pathway are considered as novel drug targets in this pathogen. Therefore, the main aim of the current study was to determine the antibacterial activity of pyridoxal 5'-phosphate (PLP), an active form of vitamin B6, against reference and clinical strains of H. pylori. Using a broad set of microbiological, physicochemical (UV absorption, LC-MS, X-ray analysis) and in silico experiments, we were able to prove that PLP inhibits adenylosuccinate synthetase (AdSS) from H. pylori by the competition with GTP (IC50eq ∼30 nM). This behaviour was attributed to formation of a Schiff base with a lysine residue (a covalent bond with Lys322 in the GTP binding site of AdSS) and was potentiated by the presence of vitamin C. This antibacterial activity of PLP gives hope for its future use against H. pylori.

Keywords: Adenylosuccinate synthetase; Helicobacter pylori; X-ray structure; antimicrobial activity; vitamin B6.

MeSH terms

  • Adenylosuccinate Synthase* / antagonists & inhibitors
  • Adenylosuccinate Synthase* / chemistry
  • Adenylosuccinate Synthase* / metabolism
  • Adenylosuccinate Synthase* / pharmacology
  • Anti-Bacterial Agents* / chemical synthesis
  • Anti-Bacterial Agents* / chemistry
  • Anti-Bacterial Agents* / pharmacology
  • Dose-Response Relationship, Drug*
  • Drug Resistance, Bacterial / drug effects
  • Enzyme Inhibitors / chemical synthesis
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacology
  • Helicobacter pylori* / drug effects
  • Helicobacter pylori* / enzymology
  • Microbial Sensitivity Tests*
  • Models, Molecular
  • Molecular Structure
  • Pyridoxal Phosphate / chemistry
  • Pyridoxal Phosphate / pharmacology
  • Structure-Activity Relationship
  • Vitamin B 6* / chemical synthesis
  • Vitamin B 6* / chemistry
  • Vitamin B 6* / pharmacology

Substances

  • Anti-Bacterial Agents
  • Vitamin B 6
  • Adenylosuccinate Synthase
  • Enzyme Inhibitors
  • Pyridoxal Phosphate

Grants and funding

Experiments conducted in Poland were financed by the project Harmonia 2015/18/M/NZ1/00776, OPUS 2018/29/B/NZ1/00140 and OPUS 2023/51/B/NZ1/01629 granted by the National Science Centre of Poland, from the University of Warsaw project IDUB PSP-501-D111-20–0004316, and by the Polish Ministry for Education and Science grant 501-D111-01–1110102. Some experiments were conducted in the NanoFun laboratories, funded by the ERDF Project POIG.02.02.00–00–025/09. X-ray studies and some other experiments were performed in the Laboratory of Biopolymers, ERDF Project POIG.02.01.00–14–122/09. Samples of WT AdSS, and initially also samples of C-His tag AdSS were obtained in Croatia, and these experiments were financed by Croatian Science Foundation (projects no. IP-2013–11-7423 and IP-2019–04-6764).