Sharing shears: Conserved protein segment activates molecular DNA scissors for DNA repair
2021-03-10
(Press-News.org) Scientists at Tokyo Institute of Technology (Tokyo Tech) have uncovered mechanisms underlying the activation of the MRN complex-- the cell's DNA scissors. Using purified yeast proteins, they demonstrated that phosphorylation of Ctp1, a homolog of a tumor-suppressor protein, plays a key role in activating MRN complex's DNA clipping activity. Intriguingly, a short segment of yeast Ctp1 or its human counterpart could stimulate endonuclease activity of their respective MRN complexes, suggesting its conserved function across species.
DNA functions as a roadmap that guides the identity and functions of cells. A glitch in the DNA can have serious deleterious effects resulting in the malfunction or loss of crucial proteins, thus affecting normal cellular function and viability. These glitches often manifest as double stranded breaks in the DNA that may occur spontaneously or from exposure to certain chemicals. To deal with these kinks, cells have evolved a DNA repair machinery that scans, identifies, and fixes breaks in the DNA by ligating the gaps. However, DNA breaks often have ''dirty ends'' that cannot be directly ligated or sealed as they are unexposed or blocked by certain proteins or irregular chemical structures. Such DNA ends thus need to first be clipped and freed so that it can be processed further. Moreover, such end-resection of DNA break ends are prerequisite for them to be accurately repaired by homologous recombination. Among such molecular scissors, or nuclease enzymes, Mre11 is a key player.
Mre11 teams up with proteins Rad50 and Nbs1 to collectively form the 'MRN' complex. The interaction of this complex with the tumor-suppressor protein CtIP in humans, has been shown to trigger the DNA clipping function of the complex (Figure 1). However, the mechanisms underlying this interaction have hitherto remained unexplored.
Now, Assistant Professor Hideo Tsubouchi and Professor Hiroshi Iwasaki from Tokyo Institute of Technology and their team have decoded the stepwise interaction and activation of the MRN complex using Ctp1 proteins in yeast, which are homologous to the human CtIP. Discussing their findings that have recently been published in PNAS, Iwasaki says, "The MRN complex is pivotal in the homologous recombination-mediated repair of DNA double stranded breaks. To better understand how CtIP influences the activity of the MRN complex, we purified yeast proteins and quantified their interactions."
The scientists found that phosphorylation or the addition of phosphate groups to Ctp1 was the key first step in activating the MRN complex. More specifically, phosphorylation enabled the physical interaction of Ctp1 with the Nbs1 protein of the complex, which was vital for subsequent endonuclease stimulation. The DNA clipping activity was extremely poor when the MRN complex was mixed with unphosphorylated Ctp1.
Furthermore, the scientists identified a short stretch of merely 15 amino acids at the C-terminal region of Ctp1 that was indispensable for the endonuclease activity of the Ctp1-stimulated MRN. Moreover, a synthetic peptide mimicking this region of Ctp1 or CtIP was able to activate the yeast or human MRN complex, respectively, suggesting that the function of the C-terminal Ctp1 is likely conserved across species and is the ultimate determinant in MRN activation.
Excited about the prospective application of their findings, Tsubouchi remarks, "Modification of the CT15 peptide can yield a strong activator or potential inhibitor of the MRN complex. Targeting this endonuclease activity can have potentially useful applications in homologous recombination-based gene editing."
With rapid advancements in recombinant DNA and molecular medicine, these findings could empower geneticists to unravel the mysteries of the genome and identify the hidden intricacies of genetic disorders with greater ease and effectiveness in the days to come.
INFORMATION:
Related Links
Helping a Helper: Uncovering How Different Proteins Cooperate in DNA Repair
https://www.titech.ac.jp/english/news/2020/046793.html
Scientists unraveling the molecular details of DNA recombination regulation
https://www.titech.ac.jp/english/news/2018/042590.html
Iwasaki Laboratory
http://www.iwasakilab.bio.titech.ac.jp/cgi-bin/wp/english-version-of-the-front-page/
About Tokyo Institute of Technology
Tokyo Tech stands at the forefront of research and higher education as the leading university for science and technology in Japan. Tokyo Tech researchers excel in fields ranging from materials science to biology, computer science, and physics. Founded in 1881, Tokyo Tech hosts over 10,000 undergraduate and graduate students per year, who develop into scientific leaders and some of the most sought-after engineers in industry. Embodying the Japanese philosophy of "monotsukuri," meaning "technical ingenuity and innovation," the Tokyo Tech community strives to contribute to society through high-impact research.
https://www.titech.ac.jp/english/
[Attachments] See images for this press release:
ELSE PRESS RELEASES FROM THIS DATE:
2021-03-10
BINGHAMTON, NY -- Star employees often get most of the credit when things go right, but also shoulder most of the blame when things go wrong, according to new research from Binghamton University, State University of New York.
The study explored the potential risks and rewards of collaborating with stars - individuals who have a reputation for exhibiting exceptional performance - and how individual performance factors into how much credit and blame is shared with collaborators.
"Stars are human, and they fail from time to time. We wanted to shift the focus away from stars, and find out what happens to the people who collaborate ...
2021-03-10
ALBUQUERQUE, N.M. -- Geoscientists at Sandia National Laboratories used 3D-printed rocks and an advanced, large-scale computer model of past earthquakes to understand and prevent earthquakes triggered by energy exploration.
Injecting water underground after unconventional oil and gas extraction, commonly known as fracking, geothermal energy stimulation and carbon dioxide sequestration all can trigger earthquakes. Of course, energy companies do their due diligence to check for faults -- breaks in the earth's upper crust that are prone to earthquakes -- but sometimes ...
2021-03-10
Eye contact is a key to establishing a connection, and teachers use it often to encourage participation. But can a robot do this too? Can it draw a response simply by making "eye" contact, even with people who are less inclined to speak up. A recent study suggests that it can.
Researchers at KTH Royal Institute of Technology published results of experiments in which robots led a Swedish word game with individuals whose proficiency in the Nordic language was varied. They found that by redirecting its gaze to less proficient players, a robot can elicit involvement from even the most reluctant participants.
Researchers Sarah Gillet and Ronald Cumbal say the results offer evidence that robots could play a productive role in educational settings.
Calling on someone by name isn't ...
2021-03-10
The protein α-synuclein is one of the most abundant proteins in the human brain. It is often referred to as the "Parkinson protein", as deposition of this protein in brain cells is a hallmark of Parkinson's disease. Despite the high interest of biomedical research in the protein, many questions concerning the function and physiology of α-synuclein in living cells still remain to be answered. For example, it was previously unclear whether and to what extent the protein binds to and interacts with internal cell components such as membranes. As such processes could play a role in the development of the disease, the team led by Konstanz-based physical chemist Professor Malte Drescher used the further development of an established measurement method called ...
2021-03-10
An article published by the researchers of the Biodiversity Unit at the University of Turku, Finland, highlights how amateur venom-extraction business is threatening scorpion species. Sustainably produced scorpion venoms are important, for example, in the pharmacological industry. However, in the recent years, there has been a dramatic increase in the number of people involved in the trade and vast numbers of scorpions are harvested from nature. This development is endangering the future of several scorpion species in a number of areas.
Scorpions have existed on Earth for over 430 million years. Currently comprising over 2,500 extant species, scorpions occur on almost all the major landmasses in a range of habitats from ...
2021-03-10
Gravity is the weakest of all known forces in nature - and yet it is most strongly present in our everyday lives. Every ball we throw, every coin we drop - all objects are attracted by the Earth's gravity. In a vacuum, all objects near the Earth's surface fall with the same acceleration: their velocity increases by about 9.8 m/s every second. The strength of gravity is determined by the mass of the Earth and the distance from the center. On the Moon, which is about 80 times lighter and almost 4 times smaller than the Earth, all objects fall 6 times slower. And on a planet of the size of a ladybug? ...
2021-03-10
A new study published Tuesday 10 March, No Smoking Day, from King's College London highlights the 'clear benefit' of using e-cigarettes daily in order to quit smoking, and supports their effectiveness when compared to other methods of quitting, including nicotine replacement therapy or medication.
Although the number of people in England who smoke has continued to fall in recent years, tobacco smoking is still the leading preventable cause of premature death and disease - killing nearly 75,000 people in England in 2019.
While e-cigarettes have been around for more than a decade, evidence on their effectiveness for helping people to ...
2021-03-10
There's a surprising amount of information stored in the hardened plaque, or calculus, between teeth. And if that calculus belongs to the remains of a person who lived in ancient times, the information could reveal new insights about the past. But the tiny samples can be difficult to work with. Now, in ACS' Journal of Proteome Research, scientists apply a new method to this analysis, finding more proteins than traditional approaches.
The human mouth is full of interesting molecules: DNA and enzymes in saliva, proteins and lipids from bits of food stuck between teeth, the bacterial ...
2021-03-10
Amsterdam, NL, March 10, 2021 - Music-based interventions have become a core ingredient of effective neurorehabilitation in the past 20 years thanks to the growing body of knowledge. In this END ...
2021-03-10
People are different. New technology is good for patients and the healthcare system. But it could also expand the already significant health disparities in Norway and other countries.
"Women and men with higher education in Norway live five to six years longer than people with that only have lower secondary school education," says Emil Øversveen, a postdoctoral fellow at the Norwegian University of Science and Technology's (NTNU) Department of Sociology and Political Science.
He is affiliated with CHAIN, the Centre for Global Health Inequalities Research. The centre works to reduce social health ...
LAST 30 PRESS RELEASES:
[Press-News.org] Sharing shears: Conserved protein segment activates molecular DNA scissors for DNA repair
