Faster diffusive dynamics of histone-like nucleoid structuring proteins in live bacteria caused by silver ions

Abstract

The antimicrobial activity and mechanism of silver ions (Ag + ) have gained broad attention in recent years. However, dynamic studies are rare in this field. Here, we report our measurement of the effects of Ag + ions on the dynamics of histone-like nucleoid structuring (H-NS) proteins in live bacteria using single-particle tracking photoactivated localization microscopy (sptPALM). It was found that treating the bacteria with Ag + ions led to faster diffusive dynamics of H-NS proteins. Several techniques were used to understand the mechanism of the observed faster dynamics. Electrophoretic mobility shift assay on purified H-NS proteins indicated that Ag + ions weaken the binding between H-NS proteins and DNA. Isothermal titration calorimetry confirmed that DNA and Ag + ions interact directly. Our recently developed sensing method based on bent DNA suggested that Ag + ions caused dehybridization of double-stranded DNA (i.e., dissociation into single strands). These evidences led us to a plausible mechanism for the observed faster dynamics of H-NS proteins in live bacteria when subjected to Ag + ions: Ag + -induced DNA dehybridization weakens the binding between H-NS proteins and DNA. This work highlighted the importance of dynamic study of single proteins in the live cells for understanding the functions of antimicrobial agents to the bacteria.

The Potential of Silver Nanoparticles for Antiviral and Antibacterial Applications: A Mechanism of Action

“…AgNPs can decrease the stability of DNA structure by electrostatic repulsion due to the DNA and AgNPs having the same polar charge [ 70 ]. Sadoon et al (2020) have shown that silver ions can interact with DNA thus causing hybridization of doubles-stranded DNA which involves dissociation of double strands into single strands by disrupting the H-bonds of DNA strands [ 71 ].…”

Controlled and localized antibiotics delivery using magnetic‐responsive beads for synergistic treatment of orthopedic infection

“…Even though plausible theories have been postulated regarding the bactericidal activity of silver, the main underlying mechanism remains controversial and probably multi‐faceted 77 . It has been reported that silver ions are able to diffuse through the bacteria membrane and attach to DNA causing dehybridization and ultimately damage to DNA 78,79 . Furthermore, the binding of silver to the bacteria membrane may disrupt its permeability and consequently impede respiratory chain processes to inhibit growth 80,81 .…”

“…77 It has been reported that silver ions are able to diffuse through the bacteria membrane and attach to DNA causing dehybridization and ultimately damage to DNA. 78,79 Furthermore, the binding of silver to the bacteria membrane may disrupt its permeability and consequently impede respiratory chain processes to inhibit growth. 80,81 Finally, the interference of silver with the membrane function results in the creation of reactive oxygen species (ROS) that lead to cell death.…”

Antibiotic-free antimicrobial poly (methyl methacrylate) bone cements: A state-of-the-art review

“…Although the exact mechanism responsible for the antimicrobial activity of Ag nanoparticles has not been established, many explanations have been put forward. Examples are uptake of free Ag ions followed by disruption of the production of an energy storage molecule (adenosine triphosphate (ATP)) and replication of DNA[ 76 ]; inactivation of the bacterial cell (cell membrane and enzymes) by the Ag ions interfering with enzymes that interact with sulfur in the protein chains and/or generating reactive oxygen species[ 54 ], which kill the cells; and Ag ions causing separation of paired strands of DNA in the bacteria[ 77 ].…”

“…Against S. epidermidis biofilm, a significant drop in bacteria viability was observed at each assayed time-point when an AFAMBC rather than a control cement was used (by a factor of between 2 and 4), indicating that the antibacterial potential of the AFAMBC is good[ 62 ]. The antibacterial action of the Cu-SBA3 cements was explained in terms of participation of reactive hydroxyl radicals that are generated in reactions that are harmful to cellular molecules, such as oxidation of proteins[ 77 ]. Notwithstanding these results, the resistance of some bacterial species, such as E. coli , against copper-containing biomaterials, was noted[ 62 ].…”