[...] some bacteria have transformed [viruses] into gene transfer agents (GTAs) that help them exchange genetic material among themselves.
This process is a type of horizontal gene transfer that allows genetic information to be shared among related bacteria rather than being restricted to inheritance by the offspring of a parent cell.
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A small, random sample of genes from the bacterium are packaged into a geometric-shaped protein structure that forms the head of a gene-transfer agent, while other proteins form a tube-like tail.
[...] After release of the GTAs from the bacterium, flexible proteins that decorate the GTA bind to and anchor the GTA to the surface of a target cell.
Then, the genetic material contained within the head of the GTA is transferred through the tail and into the target cell, with help from bacterial proteins located in the cell membrane.
Inside the target cell, other proteins bind the incoming DNA and insert it into the cell’s genome. Since genes provide the blueprint for all of the cell’s biological activities, this process may allow the [target] bacterium to acquire new, advantageous traits.
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The bacterium must weigh the benefits of shuffling genetic information against the cost. To release the gene-transfer agents, the original cell bursts and dies.
[...] There are a few conditions under which a GTA-producing bacterial cell deems it worthwhile to make this sacrifice. One is when it runs out of nutrients, particularly amino acids, which are needed to make proteins. In this case, new combinations of genes could enable the cell to acquire previously inaccessible nutrients.
Another is when the cell senses a chemical signal given off by neighbouring cells, alerting it to many related target cells nearby. In this scenario, the cell recognizes that its own death could benefit a high number of its relatives.
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[...] the first laboratory demonstration of a GTA was in the bacterium R. capsulatus and involved the transfer of genetic material that allows bacteria to resist being killed by antibiotics.
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