Even bacteria have a kind of “immune system” they use to defend themselves against unwanted intruders – in their case, viruses. Scientists at the Helmholtz Center for Infection Research (HZI) in Braunschweig, Germany, were now able to show that this defense system is much more diverse than previously thought and that it comes in multiple versions. Their goal is to use the various newly discovered versions of the CRISPR-Cas gene for the targeted manipulation of genetic information, particularly for medical purposes.
Streptococcus pyogenes, shown here while entering a cell, is one of the germs whose CRISPR-Cas system the scientists from Braunschweig have studied.
© HZI / Rohde
The human immune system’s main function is to protect us against invading bacteria, viruses, and other pathogens. To perform its job, the system has evolved into a highly complex ensemble of cells, messengers, and antibody molecules that is capable of recognizing different pathogens, defending us against them, and storing information about them.
Even the bacteria themselves are threatened by pathogens: Certain viruses, the bacteriophages (literally, “bacteria eaters”), have become specialized to invade bacterial cells and proliferate inside of them. In order to get rid of these unwanted guests, many species of bacteria make use of an arsenal of molecules that works according to similar principles as an immune system does.
The Cas enzyme recognizes DNA molecules that contain non-self genetic information, e.g. from bacteriophages, and cleaves them at specific sites. In order to recognize these molecules, a molecular copy of specific, characteristic sections of the foreign DNA is required. This copy, a kind of “molecular profile” of bacteriophage DNA and other foreign genetic material, exists as RNA, an important cellular building block, which is used, among other things, as a temporary storage site of genetic information.
The template for this profile is stored in the bacterium’s own genes, specifically in those regions scientists call CRISPR (which stands for “clustered regularly interspaced small palindromic repeats” or, more simply put, the “regular arrangement of small, symmetric repeats” in the sequence of the DNA building blocks).Together, the enzyme and the profile RNA constitute the CRISPR-Cas system.
“We were able to identify new CRISPR-Cas genes in a number of bacterial species,” says Charpentier, an HZI researcher who also teaches at Hannover Medical School (MHH). Among these species are much-feared germs like Streptococcus pyogenes and the meningitis pathogen, Neisseria meningitidis. “We have identified a number of these genes with the help of computers by examining known DNA sequences of the bacteria in question.” Charpentier’s conclusion: “The CRISPR system is not only widespread among bacteria, it also exists as an incredible range of different versions.”
Knowing about these different versions is not only of academic interest but can also be tremendously useful for gene technology: ”The CRISPR-Cas system is capable of cleaving DNA at very specific sites,” explains Charpentier. “The Cas enzyme can already be modified in such a way that it becomes active not only in bacteria but also in animal and human cell cultures.” If this kind of enzyme is specifically equipped with new RNA “profiles,” it cleaves the cell’s genome at precisely defined sites. “If you then use specific cellular repair mechanisms to mend the DNA strands and connect their loose ends, you can then specifically introduce new sections of genes into cellular DNA.”This opens considerable options for new forms of therapy. “I am certain that the CRISPR-Cas technology has tremendous potential,” says Charpentier. “Especially for medical applications like gene therapy.”
Dr. Jan Grabowski | Helmholtz-Zentrum
The balancing act: An enzyme that links endocytosis to membrane recycling
07.12.2016 | National Centre for Biological Sciences
Transforming plant cells from generalists to specialists
07.12.2016 | Duke University
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine