Invisible DNA
Scientists have "deceived" the protective system of bacteria
In an article recently published in the journal Proceedings of the National Academy of Sciences (Johnston et al., Systematic evasion of the restriction-modification barrier in bacteria), scientists from the Foresight Institute describe a new technique of genetic engineering that makes artificial DNA invisible to the protective system of bacteria. Theoretically, the method can be applied to almost any known type of bacteria, according to the institute's website.
Bacteria are everywhere. They live in the soil and in the water, on our skin and in our bodies. Some of them are pathogenic, meaning they cause diseases or infections. In order to develop effective methods of combating pathogens, researchers need to know which genes are to blame for the harmfulness.
Scientists can identify pathogenic genes using genetic engineering. Its essence is that experts add artificial DNA to a bacterial cell. However, the problem is that the bacteria that live under the constant threat of a virus attack have created complex defense systems. When a bacterial cell detects an intruder, especially foreign DNA, it quickly destroys the intruder. Modern approaches of genetic engineering often use complex manipulations to disguise artificial DNA as "native", bacterial, in order to destroy protective mechanisms. This approach sometimes works, but it requires a lot of time and financial resources.
The new strategy developed by Christopher Johnston and his colleagues works differently. Instead of adding a disguise to the man–made DNA, scientists remove a certain component of its genetic sequence - the so-called motif. The bacterial defense system needs this motif to recognize foreign DNA and effectively counterattack. Having lost the motive, the DNA created by man becomes practically invisible to the bacterium's defense system.
"Imagine a bacterium similar to an enemy submarine in a dock, and a human-made genetic tool as your soldier who needs to get inside the submarine to complete a certain task. Modern approaches suggest disguising a spy as an enemy, forcing him to approach each of the gates, allowing the guards to check his credentials, and if everything goes well, he will get inside," Johnston gave an analogy. "Our approach is to make this soldier invisible and make him slip right through the gate, remaining completely invisible to the guards."
This new method requires less time and resources. In the study, Johnston used Staphylococcus aureus bacteria as a model. At the same time, the basic strategy developed by him can be used to bypass the main protective systems of 80-90% of bacteria known today. A new genetic engineering tool opens up opportunities for the study of bacteria that have not been well studied before.
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