Featured Research

from universities, journals, and other organizations

3D Structure Of A DNA Damage Repair Complex

Date:
December 6, 2007
Source:
Universidad Autónoma de Madrid
Summary:
This is the first study that shows the 3D structure of a molecular complex found in the bacteria Mycobacterium tuberculosis that repairs DNA damage. According to the biochemical data, this reflects a stage of the search for compatible microhomologies. This is the process of seeking non complementary extremes of DNA that would never link under normal conditions, known as non-homologous end joining (NHEJ).

Bacteria with damaged (red) DNA (showed in orange). As represented graphically, two proteins are involved in the repair of the damage: Protein Ku (shaped like a ring in the figure) and LigD (showed in green) that acts like nuclease, polymerase and ligase.
Credit: Image courtesy of Universidad Autónoma de Madrid

This is the first study that shows the 3D structure of a molecular complex found in the bacteria Mycobacterium tuberculosis that repairs DNA damage. According to the biochemical data, this reflects a stage of the search for compatible microhomologies. This is the process of seeking non complementary extremes of DNA that would never link under normal conditions, known as non-homologous end joining (NHEJ). 

The double strand breaking of DNA is considered the most lethal kind of damage for our genome, since an error in its repair potentially represents cell death or tumour growth. Non-homologous end joining is a repair process for the double strand breaking of DNA which can operate at any stage of the cellular cycle, and it is essential in maintaining the genome stability in mammals.

The process uses a combination of proteins responsible for the protection and maintenance of the proximity of the ends as well as all the actions necessary to repair the rupture. As an analogy, NHEJ operates like an adhesive kit that cleans the damaged area, fills the missing parts, and glues together the loose ends, even if is inevitable that some nucleotides are changed or lost in the process.

A potential hazard of this mechanism is simultaneous ruptures, since it is possible that the strands are confused and the wrong strands are glued together, and such a translocation could activate an oncogene.

This study identifies the structural bases of the NHEJ process in the DNA of the bacteria Mycobacterium tuberculosis, and shows for the first time the 3D structure of a NHEJ repairing complex. Up until now, there was little information about the different processing activities that occur in sequential coordination during the NHEJ, either about the independent proteins of mammals, or the different parts of the same protein like in bacteria.

The union of the extremities shown in the 3D structure and described in this study, shows the stage of alignment of the ends, prior to the processing by the activity of nuclease (DNA cleaver), polymerase (DNA synthesis) and ligase (DNA binding), all carried out by the enzyme LigD (DNA repair) in the case of bacteria. This study can be extrapolated to the NHEJ of mammals.

From a more applied point of view, this analysis identifies the polymerization of the bacterial LigD as a possible target to hamper the repair process of double strand breaks in these organisms. It has been proven that the NHEJ is a source of genetic variability in bacteria, necessary for their adaptation and survival in genotoxic (toxic for DNA) environments. The selective elimination of this process could have applications such as treatments that avoid the generation of antibiotic resistant bacteria.

This research is published in the journal Science. The work was co directed by Dr. Aidan Doherty from the Sussex Centre for Genome Damage and Stability in the UK and by Dr. Luis Blanco from the Centro de Biología Molecular Severo Ochoa (CSIC-UAM). Among the Spanish participating researchers are Dr. Raquel Juárez Santos, and Dr. Angel J. Picher Serantes.


Story Source:

The above story is based on materials provided by Universidad Autónoma de Madrid. Note: Materials may be edited for content and length.


Cite This Page:

Universidad Autónoma de Madrid. "3D Structure Of A DNA Damage Repair Complex." ScienceDaily. ScienceDaily, 6 December 2007. <www.sciencedaily.com/releases/2007/11/071130235724.htm>.
Universidad Autónoma de Madrid. (2007, December 6). 3D Structure Of A DNA Damage Repair Complex. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2007/11/071130235724.htm
Universidad Autónoma de Madrid. "3D Structure Of A DNA Damage Repair Complex." ScienceDaily. www.sciencedaily.com/releases/2007/11/071130235724.htm (accessed July 28, 2014).

Share This




More Plants & Animals News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) — Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) — A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
Powered by NewsLook.com
Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Newsy (July 27, 2014) — The satellite is back under ground control after a tense few days, but with a gecko sex experiment on board, the media just couldn't help themselves. Video provided by Newsy
Powered by NewsLook.com
Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) — A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. 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