Featured Research

from universities, journals, and other organizations

The many faces of the bacterial defense system

Date:
April 30, 2013
Source:
Helmholtz Centre for Infection Research
Summary:
Even bacteria have a kind of "immune system" they use to defend themselves against unwanted intruders -- in their case, viruses. Scientists were now able to show that this defense system is much more diverse than previously thought and that it comes in multiple versions.

RohdeStreptococcus pyogenes, shown here while entering a cell, is one of the germs whose CRISPR-Cas system the scientists from Braunschweig have studied.
Credit: © HZI

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.

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.

Now, Prof. Emmanuelle Charpentier's work group has scoured the genome of several hundred bacterial species in the search of CRISPR-Cas genes -- and has made several discoveries. "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."


Story Source:

The above story is based on materials provided by Helmholtz Centre for Infection Research. Note: Materials may be edited for content and length.


Journal Reference:

  1. Krzysztof Chylinski, Anaοs Le Rhun, Emmanuelle Charpentier. The tracrRNA and Cas9 families of type II CRISPR-Cas immunity systems. RNA Biology, 2013

Cite This Page:

Helmholtz Centre for Infection Research. "The many faces of the bacterial defense system." ScienceDaily. ScienceDaily, 30 April 2013. <www.sciencedaily.com/releases/2013/04/130430131631.htm>.
Helmholtz Centre for Infection Research. (2013, April 30). The many faces of the bacterial defense system. ScienceDaily. Retrieved September 16, 2014 from www.sciencedaily.com/releases/2013/04/130430131631.htm
Helmholtz Centre for Infection Research. "The many faces of the bacterial defense system." ScienceDaily. www.sciencedaily.com/releases/2013/04/130430131631.htm (accessed September 16, 2014).

Share This



More Health & Medicine News

Tuesday, September 16, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

President To Send 3,000 Military Personnel To Fight Ebola

President To Send 3,000 Military Personnel To Fight Ebola

Newsy (Sep. 16, 2014) — President Obama is expected to send 3,000 troops to West Africa as part of the effort to contain Ebola's spread. Video provided by Newsy
Powered by NewsLook.com
Man Floats for 31 Hours in Gulf Waters

Man Floats for 31 Hours in Gulf Waters

AP (Sep. 16, 2014) — A Texas man is lucky to be alive after he and three others floated for more than a day in the Gulf of Mexico when their boat sank during a fishing trip. (Sept. 16) Video provided by AP
Powered by NewsLook.com
EU Ministers and Experts Meet to Discuss Ebola Reponse

EU Ministers and Experts Meet to Discuss Ebola Reponse

AFP (Sep. 15, 2014) — The European Commission met on Monday to coordinate aid that the EU can offer to African countries affected by the Ebola outbreak. Duration: 00:58 Video provided by AFP
Powered by NewsLook.com
Despite The Risks, Antibiotics Still Overprescribed For Kids

Despite The Risks, Antibiotics Still Overprescribed For Kids

Newsy (Sep. 15, 2014) — A new study finds children are prescribed antibiotics twice as often as is necessary. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins