The protein forms a filament, which grows and shrinks primarily by one monomer at a time, the researchers report in the August issue of the journal Cell.
RecA is a DNA recombination protein found in the gut bacterium E. coli. A human homolog, called Rad51, interacts with many proteins, including BRCA2, whose mutation increases susceptibility to breast and ovarian cancers. A better understanding of how these proteins function could help our understanding of cancer.
"Our measurement technique provides a way of counting the number of individual monomers bound to DNA in real time," said Taekjip Ha, a professor of physics at Illinois and a Howard Hughes Medical Institute investigator. "With that, we can determine the kinetic rates for reactions occurring at either end of the protein filament."
During the recombination process, RecA binds with DNA to form a filament that spirals around the DNA. The filament can grow in either direction, and can advance on the DNA by growing at the leading end and dissociating at the trailing end.
To study the dynamics of RecA, the researchers used a highly sensitive single-molecule fluorescence resonance energy transfer (FRET) technique that Ha and colleagues developed.
To use FRET, researchers first attach two dye molecules – one green and one red – to the molecule they want to study. Next, they excite the green dye with a laser. Some of the energy moves from the green dye to the red dye, depending upon the distance between them.
The researchers then measure the brightness of the two dyes simultaneously. The changing ratio of the two intensities indicates the relative movement of the two dyes, and therefore the motion of the molecule or its change in size.
The technique revealed intricate details of how RecA nucleates to form a filament, how the filament changes shape, and how the filament removes proteins from DNA.
"Contrary to our initial expectations, both ends of the RecA filament continually grow and shrink, but a higher binding rate at one end causes the filament to grow primarily in one direction," Ha said. "We also learned that as the filament grows and shrinks, it does so by one protein unit at a time."
Following recombination proteins step by step could further help researchers determine in what ways cancer-causing proteins are defective, and perhaps find ways to correct them.
James E. Kloeppel | EurekAlert!
Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care
Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses