How silver ions kill bacteria?

By studying proteins at the molecular level, scientists hope to understand how silver can be used to fight 'superbugs'.

The antimicrobial activity and mechanism of silver ions (Ag+) have gained widespread attention in recent years. Although, it is still mysterious how kills bacteria.

Scientists at the University of Arkansas have taken a step forward towards it. They shed light on the process by taking a gander at the dynamics of proteins in live bacteria at the molecular level.

Traditionally, bioassays were used to measure the antimicrobial effects of silver. The process compares the impact of a substance on a test organism against a standard, untreated preparation.

Yong Wang, assistant professor of physics and an author of the study, said“While these methods are effective, they typically produce only snapshots in time.”

Using an advanced technique called single-particle-tracking photoactivated localization microscopy, scientists observed and tracked a particular protein found in E. coli bacteria over time. Scientists found that silver ions sped up the dynamics of the protein, opposite of what they thought would happen.

Wang said, “It is known that silver ions can suppress and kill bacteria; we thus expected that everything slowed down in the bacteria when treated with silver. But, surprisingly, we found that the dynamics of this protein became faster.”

The observation of DNA separation caused by silver ions came from earlier work that Wang and colleagues had done with bent DNA. Their approach, now patent-pending, was to put a strain on DNA strands by bending them, thus making them more susceptible to interactions with other chemicals, including silver ions.

Wang said, “The National Science Foundation-funded study validated the idea of investigating the dynamics of single proteins in live bacteria, an approach that could help researchers understand the real-time responses of bacteria to silver nanoparticles, which have been proposed for fighting against so-called “superbugs” that are resistant to commonly prescribed antibiotics.”

“What we want to do eventually is to use the new knowledge generated from this project to make better antibiotics based on silver nanoparticles.”

Journal Reference:
  1. Silver Ions Caused Faster Diffusive Dynamics of Histone-Like Nucleoid-Structuring Proteins in Live Bacteria. DOI: 10.1128/AEM.02479-19

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