American scientists at the nanoscale have found out how silver ions act on bacteria, including those resistant to antibiotics. The research results are published in the journal Applied and Environmental Microbiology.
The antimicrobial properties of silver have been known for centuries, although how exactly silver kills bacteria remains largely a mystery. Traditionally, studies of the antibacterial effect of silver have been limited to comparing the properties of organisms treated with preparations containing silver with controls. However, this gave only a quantitative assessment, not allowing us to understand the very physical mechanism of metal action on microorganisms.
American scientists from the University of Arkansas have analyzed the process of action of silver ions on the proteins of living bacteria at the molecular level. To do this, they used an advanced imaging technique - the method of photoactivated localization microscopy with tracking of single particles - to observe over time the dynamics of certain proteins in Escherichia coli, which is a model organism for microbiological research.
Scientists expected to see that silver ions would slow down the activity of bacteria, but they saw the opposite - silver ions accelerated the diffusion dynamics of proteins.
“It is known that silver ions can inhibit and kill bacteria, so we expected that the silver treatment in bacteria would slow down everything. But unexpectedly, we found that the dynamics of the protein accelerated, - quoted in a press release from the university, the words of the head of the study, associate professor of physics Yong Wang (Yong Wang).
By studying the behavior of proteins more closely, the scientists noticed that silver ions cause the paired strands of DNA in bacteria to separate and weaken the bond between the protein and DNA. Calorimetric analyzes have confirmed that DNA and silver ions interact directly.
“If so, you can explain the faster protein dynamics caused by silver,” Wang says. - When a protein is bound to DNA, it moves slowly in bacteria along with DNA, which is a huge molecule. On the contrary, when treated with silver, proteins fall off the DNA, moving by themselves and, therefore, moving faster."
Wang and his colleagues have observed the splitting of DNA strands caused by silver ions during their previous study with bent DNA. The experiment then consisted of increasing the tension in the bent DNA strands to make them more susceptible to interactions with other chemicals, including silver ions.
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“Ultimately, we want to use the new knowledge gained from this project to create more effective antibiotics based on silver nanoparticles,” Wang said.
Scientists hope that their results will help create drugs based on silver nanoparticles to fight the so-called "superbugs" - bacteria resistant to common antibiotics - which have become a real threat to public health on a global scale in recent years.