Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Protein scaffold

27.05.2015

Right before a cell starts to divide to give birth to a daughter cell, its biochemical machinery unwinds the chromosomes and copies the millions of protein sequences comprising the cell's DNA, which is packaged along the length of the each chromosomal strand. These copied sequences also need to be put back together before the two cells are pulled apart. Mistakes can lead to genetic defects or cancerous mutations in future cell generations.

Just like raising a building requires scaffolding be erected first, cells use biochemical scaffolding machinery to reassemble copied genomic fragments back into chromosomes. Researchers at the Okinawa Institute of Science and Technology Graduate University (OIST) have mapped the points along the genome where a scaffolding protein crucial to maintaining the genome's structure binds. The paper was published in Genes to Cells.


The cells on the left are normal yeast cells, in the process of dividing successfully. As can be seen, the replicated chromosomes have completely separated from the original. The cells on the right produced mutant condensin and their chromosomes were unable to segregate properly.

Credit: OIST

The protein complex, called condensin, is one of many that become active when cells replicate. Researchers in OIST's G0 Cell Unit used fission yeast to find the binding sites of this particular protein complex along chromosomal DNA. This type of yeast shares many important genes with us and also has one of the two known condensin complexes in humans. It also undergoes cell division by first creating copies of chromosomes like most human cells and has a very fast replication cycle, all of which facilitated the study.

The OIST researchers found that the largest amount of condensin aggregates at the centromere, the central knot tying together the two replicated chromosomes. In a lot of cancerous cells, the centromere has an unnatural shape, which could be caused by a malfunction in the relevant cell's scaffolding machinery.

Large amounts of condensin also accumulate at areas where RNA is created. In humans and all multicellular organisms, three different types of RNA producing enzymes control how genes are transcribed. Thus, condensin is crucial to passing on genes correctly.

Condensin also helps preserve the genome in challenging environments. OIST researchers bumped up the heat from 20 degrees to 36 degrees centigrade over 9 minutes, and found that condensin accumulated around heat-shock protein (Hsp) genes after replication. Hsp genes are a family of proteins produced by cells in stressful situations, ranging from high temperatures to ultraviolet light exposure to maintain genomic integrity.

The researchers also engineered a yeast strain where a mutant condensin was produced by the cell when it went into figurative labor. In this mutated strain, there were massive errors in disentangling the separately copied chromosomes from the original. DNA content in the mutant cells increased and some of the resulting cell sizes were larger.

Larger cells need more energy to survive and condensin could be crucial to maintaining appropriate DNA content and cell sizes across cellular generations.

Extraneous structures like RNA and bound proteins are typically present along the length of chromosomes. Accommodating these extra structures into the daughter cell's nucleus might be what increases the overall cell size.

"While these macromolecules are important for the parent cell, they pose hindrances during cell division to segregating the copied chromosomes to daughter cells properly," said Dr. Norihiko Nakazawa, of OIST's G0 Cell Unit, the paper's first author.

The OIST researchers speculate that condensin is trimming the hedgerow of the genome during the replication and dividing phase. They further speculate that these eliminated macromolecules might be regenerated by the cellular machinery of the daughter cell when necessary.

At this point, the relevant biochemical processes by which condensin works remain to be apprehended. The OIST study concentrates on only one type of condensin. Where the second type of condensin, which is present in humans and other multicellular organisms, binds during cell division is another future line of enquiry.

Media Contact

Kaoru Natori
kaoru.natori@oist.jp
81-989-662-389

 @oistedu

http://www.oist.jp/ 

Kaoru Natori | EurekAlert!

Further reports about: DNA Protein RNA cell division chromosomes daughter genes humans protein complex replication

More articles from Life Sciences:

nachricht Researchers develop eco-friendly, 4-in-1 catalyst
25.04.2017 | Brown University

nachricht Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017
25.04.2017 | Laser Zentrum Hannover e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

NASA's Fermi catches gamma-ray flashes from tropical storms

25.04.2017 | Physics and Astronomy

Researchers invent process to make sustainable rubber, plastics

25.04.2017 | Materials Sciences

Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017

25.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>