Corporate Banner
Satellite Banner
Scientific Community
Become a Member | Sign in
Home>News>This Article

Team Solves Mystery Associated with DNA Repair

Published: Wednesday, December 19, 2012
Last Updated: Wednesday, December 19, 2012
Bookmark and Share
Every time a human or bacterial cell divides it first must copy its DNA. Specialized proteins unzip the intertwined DNA strands while others follow and build new strands, using the originals as templates.

Whenever these proteins encounter a break – and there are many – they stop and retreat, allowing a new cast of molecular players to enter the scene.

Scientists have long sought to understand how one of these players, a repair protein known as RecA in bacterial cells, helps broken DNA find a way to bridge the gap. They knew that RecA guided a broken DNA strand to a matching sequence on an adjoining bit of double-stranded DNA, but they didn’t know how. In a new study, researchers report they have identified how the RecA protein does its job.

“The puzzle for scientists has been: How does the damaged DNA look for and find its partner, the matching DNA, so that it can repair itself?” said University of Illinois physics professor Taekjip Ha, who led the study. “Because the genomic DNA is millions of bases long, this task is much like finding a needle in a haystack. We found the answer to how the cell does this so quickly.”

The research is described in a paper in eLife, a new open-access journal supported by the Howard Hughes Medical Institute (HHMI), the Max Planck Society and the Wellcome Trust. Ha is an HHMI investigator. The National Science Foundation provided primary funding for this work.

DNA repair is vital to health, vitality and longevity. Disruptions of the process can lead to the early onset of diseases associated with aging or cancer in animals. The breast cancer mutation known as BRCA2, for example, disrupts a gene involved in loading Rad51 (the human equivalent of RecA) onto a broken DNA strand to begin the process of repair.

Previous studies have shown that in bacteria, RecA forms a filament that winds itself around a broken, single strand of DNA. Like a matchmaker trying to find a partner for an unpaired dancer, it scours the corresponding DNA strands for a sequence that will pair up perfectly with the broken strand. Once it finds the sequence, the broken strand steps in and chemically bonds to its new partner, displacing one of the unbroken strands (which eventually pairs with the other broken strand). This elaborate molecular square dance allows the cell to go back to the work of duplicating its genome. Each broken strand now is paired with an unbroken one, and uses the intact strand as a template for replication. (Watch an animation about this process.)

“If a break in DNA occurs, you have to repair it,” Ha said. “We wanted to know how RecA helps the DNA find a sequence complementary to it in the sea of genomic DNA, and how it does it so quickly.”

To answer this question, the researchers made use of fluorescence resonance energy transfer (FRET) to observe in real time the interaction of the RecA protein and the DNA. FRET uses fluorescent molecules whose signals vary in intensity depending on their proximity to one another. By labeling a single DNA strand bound by RecA and putting a different fluorescent label on a stretch of double-stranded DNA, the researchers could see how the molecules interacted with one another.

The team determined that RecA that is bound to a broken, single-stranded DNA molecule actually slides back and forth along the double-stranded DNA molecule searching for a match.

“We discovered that this RecA filament can slide on double-stranded DNA for a span of sequences covering about 200 base pairs of DNA,” Ha said. “This is how one strand of DNA can be exchanged with another from a different DNA duplex. That’s the process called
‘recombination.’ ”

The discovery explains how DNA repair can occur so quickly, Ha said.

“We did a calculation that found that without this kind of process that we discovered, then DNA repair would be 200 times slower,” he said. “So your DNA would not be repaired quickly and damage would accumulate, possibly leading to serious diseases.”

Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,700+ scientific posters on ePosters
  • More than 3,800+ scientific videos on LabTube
  • 35 community eNewsletters

Sign In

Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

First Artificial Ribosome Designed
Researchers at the University of Illinois at Chicago and Northwestern University have engineered a tethered ribosome that works nearly as well as the authentic cellular component, or organelle, that produces all the proteins and enzymes within the cell.
Friday, July 31, 2015
How TALENs Find Their Way Around the Genome
Scientists from the University of Illinois Urbana-Champaign have discovered how a genome editing technology finds its way to a specific location in the genome.
Thursday, June 04, 2015
Team Discovers How Microbes Build a Powerful Antibiotic
Researchers discovery opens up new avenues of research into thousands of similar molecules.
Wednesday, October 29, 2014
It Takes A(n Academic) Village to Determine an Enzyme's Function
Scientists have sequenced the genomes of nearly 6,900 organisms, but they know the functions of only about half of the protein-coding genes thus far discovered.
Wednesday, October 02, 2013
Odd Biochemistry Yields Lethal Bacterial Protein
While working out the structure of a cell-killing protein produced by some strains of the bacterium Enterococcus faecalis, researchers stumbled on a bit of unusual biochemistry.
Wednesday, January 23, 2013
Research Conducted on Ion Channels
Researchers see subtle differences between two branches of an important family of neurotransmitter-gated ion channels by using a high-resolution single-molecule study technique.
Thursday, July 28, 2011
Computational Microscope Peers into the Working Ribosome
Two new studies reveal how the ribosome interacts with other molecules to assemble new proteins and guide them toward their destination in biological cells.
Wednesday, November 25, 2009
Newly Found DNA Catalysts Cleave DNA with Water Molecule
The deoxyribozymes accomplish the DNA cleavage with the sequence-selectivity and site-selectivity required for a practical catalyst, the researchers say.
Wednesday, August 19, 2009
Researchers use new Approach to Predict Protein Function
The study describes an integrated approach using experimental techniques, computational techniques and X-ray crystallography for predicting the function of a protein.
Tuesday, July 17, 2007
Compound Reveals Link Between Signaling Protein And Cell Migration
The protein, known as RKIP, controls activity of kinases, a type of enzyme that acts as a key component in the biochemical signaling pathways responsible for determining almost all cellular activity.
Wednesday, September 28, 2005
Scientific News
Biomarker Predicting Transplant Complications May be Key to Treating Them
A protein that can be used to predict if a stem cell transplant patient will suffer severe complications may also be the key to preventing those complications, an international research team based at the Indiana University School of Medicine reported Wednesday.
New Protein Cleanup Factors Found to Control Bacterial Growth
UMass Amherst researchers characterize previously mysterious proteolysis factors.
Proteins with ALS, Cancer Role Do Not Assume a Regular Shape
Our cells contain proteins, essential to functions like protein creation and DNA repair but also involved in forms of ALS and cancer, that never take a characteristic shape, a new study shows.
Key to Natural Detoxifier’s Reactivity Discovered
Results have implications for health, drug design and chemical synthesis.
New Protein Found in Immune Cells
Immunobiologists from the University of Freiburg discover Kidins220/ARMS in B cells and demonstrate its functions.
Cell's Waste Disposal System Regulates Body Clock Proteins
New way to identify interacting proteins could identify potential drug targets.
How a Molecular Motor Untangles Protein
Diseases such as Alzheimer’s, Parkinson’s and prion diseases, all involve “tangled” proteins.
Compound Doubles Up On Cancer Detection
Researchers have found that tagging a pair of markers found almost exclusively on a common brain cancer yields a cancer signal that is both more obvious and more specific to cancer.
How Cell Growth Triggers Cell Division
Researchers in Jan Skotheim's lab have discovered a previously unknown mechanism that controls how large cells grow, an insight that could one day provide insight into attacking diseases such as cancer.
Probing the Forces Involved in Creating The Mitotic Spindle
Scientists at The Rockefeller University reveal new insights into the mechanical forces that govern elements of the mitotic spindle formation.
Scroll Up
Scroll Down
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,700+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
3,800+ scientific videos