Theoretical Insight into the Phosphate-Targeted Silver's Antibacterial Action: Differentiation between Gram (+) and Gram (-) Bacteria

Inorg Chem. 2022 Jul 4;61(26):10089-10100. doi: 10.1021/acs.inorgchem.2c01085. Epub 2022 Jun 20.

Abstract

Although silver is one of the first metals finding broad applications in everyday life, specific key points of the intimate mechanism of its bacteriostatic/bactericidal activity lack explanation. It is widely accepted that the antimicrobial potential of the silver cation depends on the composition and thickness of the bacterial external envelope: the outer membrane in Gram-negative bacteria is more prone to Ag+ attack than the cell wall in Gram-positive bacteria. The major cellular components able to interact strongly with Ag+ (teichoic acids, phospholipids, and lipopolysaccharides) contain mono/diesterified phosphate moieties. By applying a reliable DFT/SMD methodology, we modeled the reactions between the aforementioned constituents in typical Gram-positive and Gram-negative bacteria and hydrated Ag+ species, thus disclosing the factors that govern the process of metal-model ligand complexation. The conducted research indicates thermodynamically possible reactions in all cases but still a greater preference of the Ag+ toward the constituents in Gram-negative bacteria in comparison with their counterparts in Gram-positive bacteria. The observed tendencies shed light on the specific interactions of the silver cation with the modeled phosphate-containing units at the atomic level.

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacteria
  • Cations
  • Gram-Negative Bacteria
  • Gram-Positive Bacteria
  • Metal Nanoparticles*
  • Microbial Sensitivity Tests
  • Phosphates / pharmacology
  • Silver* / pharmacology

Substances

  • Anti-Bacterial Agents
  • Cations
  • Phosphates
  • Silver