Viruses cannot only cause illnesses in humans, they also infect bacteria. Those protect themselves with a kind of ‘immune system’ which – simply put – consists of specific sequences in the genetic material of the bacteria and a suitable enzyme.
Streptococcus pyogenes is one of the bacteria in which the HZI scientists have studied the CRISPR-Cas system. © HZI / Rohde
It detects foreign DNA, which may originate from a virus, cuts it up and thus makes the invaders harmless. Scientists from the Helmholtz Centre for Infection Research (HZI) in Braunschweig have now shown that the dual-RNA guided enzyme Cas9 which is involved in the process has developed independently in various strains of bacteria.
This enhances the potential of exploiting the bacterial immune system for genome engineering.
Even though it has only been discovered in recent years the immune system with the cryptic name ‘CRISPR-Cas’ has been attracting attention of geneticists and biotechnologists as it is a promising tool for genetic engineering. CRISPR is short for Clustered Regularly Interspaced Palindromic Repeats, whereas Cas simply stands for the CRISPR-associated protein. Throughout evolution, this molecule has developed independently in numerous strains of bacteria. This is now shown by Prof Emmanuelle Charpentier and her colleagues at the Helmholtz Centre for Infection Research (HZI) who published their finding in the international open access journal Nucleic Acids Research.
The CRISPR-Cas-system is not only valuable for bacteria but also for working in the laboratory. It detects a specific sequence of letters in the genetic code and cuts the DNA at this point. Thus, scientists can either remove or add genes at the interface. By this, for instance, plants can be cultivated which are resistant against vermins or fungi. Existing technologies doing the same thing are often expensive, time consuming or less accurate. In contrast to them the new method is faster, more precise and cheaper, as fewer components are needed and it can target longer gene sequences.
Additionally, this makes the system more flexible, as small changes allow the technology to adapt to different applications. “The CRISPR-Cas-system is a very powerful tool for genetic engineering,“ says Emmanuelle Charpentier, who came to the HZI from Umeå and was awarded with the renowned Humboldt Professorship in 2013. “We have analysed and compared the enzyme Cas9 and the dual-tracrRNAs-crRNAs that guide this enzyme site-specifically to the DNA in various strains of bacteria.” Their findings allow them to classify the Cas9 proteins originating from different bacteria into groups. Within those the CRISPR-Cas systems are exchangeable which is not possible between different groups.
This allows for new ways of using the technology in the laboratory: The enzymes can be combined and thereby a variety of changes in the target-DNA can be made at once. Thus, a new therapy for genetic disorders caused by different mutations in the DNA of the patient could be on the horizon. Furthermore, the method could be used to fight the AIDS virus HIV which uses a receptor of the human immune cells to infect them. Using CRISPR-Cas, the gene for the receptor could be removed and the patients could become immune to the virus. However, it is still a long way until this aim will be reached.
Still those examples show the huge potential of the CRISPR-Cas technology. “Some of my colleagues already compare it to the PCR,” says Charpentier. This method, developed in the 1980s, allows scientists to ‘copy’ nucleic acids and therefore to manifold small amounts of DNA to such an extent that they can be analysed biochemically. Without this ground-breaking technology a lot of experiments we consider to be routine would have never been possible.
Charpentier was not looking for new molecular methods in the first place. “Originally, we were looking for new targets for antibiotics. But we found something completely different,” says Charpentier. This is not rare in science. In fact some of the most significant scientific discoveries have been made incidentally or accidentally.Original publication:
Nucleic Acids Research, 2013, DOI: 10.1093/nar/gkt1074
The department “Regulation in Infection Biology” studies how the expression of bacterial RNA and bacterial proteins is controlled. Both factors contribute to the establishment and the course of an infection.The Helmholtz Centre for Infection Research (HZI)
Dr. Jan Grabowski | Helmholtz-Zentrum
Bacteria as pacemaker for the intestine
22.11.2017 | Christian-Albrechts-Universität zu Kiel
Researchers identify how bacterium survives in oxygen-poor environments
22.11.2017 | Columbia University
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
22.11.2017 | Business and Finance
22.11.2017 | Physics and Astronomy
22.11.2017 | Physics and Astronomy