Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Mechanism Discovered for DNA Recombination and Repair

12.09.2007
A biochemistry research team led by Dr. Andrew H.-J. Wang and Dr. Ting-Fang Wang at the Institute of Biological Chemistry, Academia Sinica(IBCAS), has discovered that the RecA family recombinases function as a new type of rotary motor proteins to repair DNA damages.

The team has recently published two structural biology articles related to RecA family recombinases. One paper is to be published in the online, open-access journal PLoS ONE on September 12, 2007 and the other has been already published in the Nucleic Acids Research on Feb. 28, 2007.

Homologous recombination (HR) is a mechanism that repairs damaged DNA with perfect accuracy, it utilizes the homologous sequence from a partner DNA as a template. This process involves the bringing together of 2 DNA molecules, a search for homologous sequences, and exchange of DNA strands.

RecA family proteins are the central recombinases for HR. The family includes prokaryotic RecA, archaeal RadA, and eukaryotic Rad51 and Dmc1. They have important roles in cell proliferation, genome maintenance, and genetic diversity, particularly in higher eukaryotes. For example, Rad51-deficient vertebrate cells accumulate chromosomal breaks before death. Rad51 and its meiosis-specific homolog, Dmc1, are also indispensable for meiosis, a specialized cell cycle for production of gametes. Mammalian Rad51 and Dmc1 proteins are known to interact with tumor suppressor proteins such as BRCA2.

... more about:
»ATP »DNA »Filament »RadA »RecA »helical »homolog

Since scientists discovered RecA family proteins, it has been assumed that RecA (and other homologs) forms only 61 right-handed filaments (six protein monomers per helical turn), and then hydrolyzes ATP to promote HR and recombinational DNA repair. Whereas a controversial puzzle came out, how the energy of ATP facilitating DNA rotation during the strand exchange reaction.

By X-ray crystallography and atomic force microscopy approaches, Dr. Wangs’ team provided the answer. They reported that archaeal Sulfolobus solfataricus RadA proteins can also self-polymerize into a 31 right-handed filament with 3 monomers per helical turn (reported in PLoS ONE) and a 43 right-handed helical filament with 4 monomers per helical turn (reported in Nucleic Acids Research).

Additional biophysical and biochemical analyses revealed that RecA family proteins may couple ATP binding and hydrolysis to the DNA strand exchange reaction in a manner that promotes clockwise axial rotation of nucleoprotein filaments. Specially, the 61 RadA helical filament undergoes clockwise axial rotation in 2 discrete 120° steps to the 31 extended right-handed filament and then to the 43 left-handed filament. As a result, all the DNA-binding motifs (denoted L1, L2 and HhH) in the RadA proteins move concurrently to mediate DNA binding, homology pairing, and strand exchange, respectively. Therefore, the energy of ATP is used to rotate not only DNA substrates but also the RecA family protein filaments.

This new model is in contrast to all current hypotheses, which overlooks the fact that RecA family proteins are flexible enough to form both right-handed and left-handed helical filaments. From this perspective, these researchers in Taiwan have opened a new avenue for understanding the molecular mechanisms of RecA family proteins.

Andrew Hyde | alfa
Further information:
http://www.plosone.org/doi/pone.0000858

Further reports about: ATP DNA Filament RadA RecA helical homolog

More articles from Life Sciences:

nachricht A novel synthetic antibody enables conditional “protein knockdown” in vertebrates
20.08.2018 | Technische Universität Dresden

nachricht Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.

The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

A novel synthetic antibody enables conditional “protein knockdown” in vertebrates

20.08.2018 | Life Sciences

Metamolds: Molding a mold

20.08.2018 | Information Technology

It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

20.08.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>