Like most organisms, the best way to destroy invaders is to chop them up. When a bacterium sees a virus, it may use a host of immune strategies to slice up its genome using a popular laboratory tool.
A new study shows that the defense strategies ofbacteria work together. Many scientists have used one or both of these systems for their research, but we did not.
The mechanism is reminiscent of our own multi-pronged immune response.
There is multi-step protection.
As soon as the virus enters the cell, the bacterium uses restriction enzymes to leave short DNA. The more sophisticated system comes later. While the restriction enzyme chops up viral DNA with the crudeness of a lawn mower, it is like a razor-sharp shear used by a gardener. By aligning it to a guide targeting a specific genetic sequence, it slit the viral invader.
Both types of bacterial defenses are used by biologists, who use them for a variety of reasons. In the 70s, scientists were able to clone and study single genes with the help of restriction enzymes. Ten years ago, technology based on CRISPR-Cas gave scientists the means to edit genomes in living cells and organisms.
A graduate fellow in Marraffini's lab found that the strategies of the bacterium work better together than on their own. When Staph are protected only by restriction enzymes, their defenses are short-lived because some of the viruses will eventually start shielding their DNA, and after a while, their study shows, thebacteria growing in the dish will start to dwindle. They recover quickly if Staph has access to both systems.
The two systems work in concert, with segments clipped by restriction enzymes helping the CRISPR-Cas machinery find the viruses and put an end to the infections.
It is a bit like vaccination, Marraffini says.
It is possible that the findings will help us understand how Staph defends itself from viruses, as well as make us better equipped to defend ourselves from Staph, a species that is notorious for its ability to become resistant to antibiotics. Last year, Marraffini's team found that the bacterium uses its CRISPR-Cas system to develop multidrug resistance. One day scientists will be able to manipulate the system with drugs in order to fight Staph infections that don't respond to other treatments.
More information: Pascal Maguin et al, Cleavage of viral DNA by restriction endonucleases stimulates the type II CRISPR-Cas immune response, Molecular Cell (2022). DOI: 10.1016/j.molcel.2022.01.012 Journal information: Molecular Cell Citation: How bacteria 'self-vaccinate' against viral invaders (2022, March 25) retrieved 25 March 2022 from https://phys.org/news/2022-03-bacteria-self-vaccinate-viral-invaders.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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