Scientists have developed a new approach to genetically engineer bacteria by making human-made DNA invisible to a bacterium’s defenses. In theory, the method can be applied to almost any type of bacteria.
A Simple approach to stay healthy is to defend the pathogens. We are prone to illness when we are subjected to pathogens. To avoid bacteria is nearly impossible because these tiny creatures are everywhere. These are the conquerors of the world which are almost omnipresent they survive in the soil and water, on our skin and in our bodies. Most of them are beneficial but some are pathogenic, meaning they cause disease or infection.
To defend pathogens effective treatments needs to be designed, researchers need to know the specific genes which are to be blamed for pathogenicity.
Pathogenicity of genes can be identified through genetic engineering, which involves adding human-made DNA into a bacterial cell. But the problem is bacteria have evolved with time and their defense system is highly updated which protect them against foreign invaders- especially foreign DNA.
Bacterial mechanism system is the smart one, which is acquired naturally. When a bacterial cell detects it has been penetrated by foreign DNA, it quickly destroys the trespasser. Bacteria live under constant threat of attack by a virus, so they have developed incredibly effective defenses against those threats.
Hence to defend this smart system current genetic approach is to disguise the human-DNA and trick the bacterium into thinking the intruder is a part of its DNA. To get past this barrier, scientists add specific modifications to disguise the human-made DNA. This approach sometimes works but can take considerable time and resources. But the drawback of this process is it requires highly specific modification and is expensive and time- consuming.
Also view: THE EMERGING GENE EDITING TOOL: CRISPR-Cas9
Dr Christopher Johnston and his colleagues at the Forsyth Institute published a paper in the Proceedings of the National Academy of Sciences journal. The paper describes a new technique to genetically engineer bacteria by making human-made DNA invisible to a bacterium’s defenses. In theory, the method can be applied to almost any type of bacteria.
The defense system of bacteria is so alert and exact that, when scientists want to place human-made DNA into bacteria, they confront the same defense systems that protect bacteria against a virus, Johnston explained.
Hence the researchers came up with the novel idea. Here the scientists used Staphylococcus aureus bacteria as a model. In this experiment, the scientists removed a ‘motif’ which is an amino acid sequence pattern which has a biological significance. To counter-attack, the bacterial defense system needs this motif to be present to recognize foreign DNA. When the motif is removed the human-made DNA essentially becomes invisible to the bacterium’s defense system.
“Imagine a bacterium like an enemy submarine in a dry-dock, and a human-made genetic tool as your soldier that needs to get inside the submarine to carry out a specific task. The current approaches would be like disguising the spy as an enemy soldier, having them walk up to each gate, allowing the guards to check their credentials, and if all goes well, they’re in. Our approach is to make that soldier invisible and have them sneak straight through the gates, evading the guards entirely.”
-Johnston is a researcher in the Vaccine and Infectious Disease Division at the Fred Hutchinson Cancer Research Center and lead author of the paper.
Advantages of this method are it requires less time and few resources when compared to current techniques. And the underlying strategy he developed can be used to sneak past these major defense systems that exist in 80 to 90 per cent of bacteria that are known today. This new genetic engineering tool provides a way to research on bacteria that haven’t been studied before. Scientists usually lack time and resources, hence they tend to work with bacteria which already have been studied. With this new tool now researcher can broaden their study and engineer more clinically relevant bacteria.
“Bacteria are the drivers of our planet, the capacity to engineer bacteria has profound implications for medicine, for agriculture, for the chemical industry, and the environment.”
Dr Gary Borisy, a Senior Investigator at the Forsyth Institute and co-author of the paper.
1. Christopher D. Johnston, Sean L. Cotton, Susan R. Rittling, Jacqueline R. Starr, Gary G. Borisy, Floyd E. Dewhirst, Katherine P. Lemon | Systematic evasion of the restriction-modification barrier in bacteria.