MOSCOW, March 22. /TASS/ Scientists discovered new types of CRISPR-CAS systems of adaptive bacterial immunity, Skoltech’s press office said.

The work of joint research team from Skolkovo Institute of Science and Technology (Skoltech), the National Institutes of Health (NIH; USA) and the Massachusetts Institute of Technology (MIT; USA) was published in the journal Nature Reviews Microbiology.

In nature, CRISPR-Cas systems are used by bacteria to defend against invading viruses. In the CRISPR-Cas, bacteria store the sequences of the viral genome, so the genes of the Cas proteins act like scissors and can cut the DNA at known points. If a bacteria is attacked by a virus, it can recognize the viral DNA by means of CRISPR-Cas and then destroy it with Cas proteins. It is the ability of CRISPR-Cas system to cut DNA at exactly the predefined locations that enable it to create new technologies for genome editing, making it possible for instance to treat genetic diseases.

"Using the systematic bioinformatics search in DNA sequences from the genome databases, we predicted new systems. The genes of newly disclosed systems are quite unusual, and the CRISPR-Cas systems are unlike those studied before. We are almost sure that now all the main types of CRISPR-Cas systems have been classified," commented Sergey Shmakov, the first author of the study and Skoltech PhD student.

As a result of the evolutionary arms race between viruses and bacteria, an incredible diversity of CRISPR-Cas systems exists in nature.

In the new study, scientists performed a large-scale bioinformatics analysis and identified previously unknown types of CRISPR-Cas systems that may have a broad range of uses in the field of genetic engineering. The researchers believe that some of the discovered CRISPR-Cas systems might be applied to developing innovative tools for genome editing and regulation.

For example, the VI-B type CRISPR-Cas system has novel proteins that may regulate its activity. Another discovery, the V-U system, contains comparatively small Cas proteins which makes it highly attractive for genetic engineering purposes because it is relatively easy for bioengineers to work with small proteins and deliver them to various kinds of cells.