Featured Research

from universities, journals, and other organizations

What holds chromosomes together? Structure of DNA-packaging proteins described

Date:
January 28, 2013
Source:
Max Planck Institute of Biochemistry
Summary:
To ensure that the genetic material is equally and accurately distributed to the two daughter cells during cell division, the DNA fibers must have an ordered structure and be closely packed. Scientists have now elucidated the structure of a ring-shaped protein complex (SMC-kleisin), which ensures order in this packaging process.

SMC-Kleisin-Complex.
Credit: Image courtesy of Max Planck Institute of Biochemistry

To ensure that the genetic material is equally and accurately distributed to the two daughter cells during cell division, the DNA fibers must have an ordered structure and be closely packed. At the Max Planck Institute of Biochemistry in Martinsried near Munich scientists have now elucidated the structure of a ring-shaped protein complex (SMC-kleisin), which ensures order in this packaging process. Together with their cooperation partners at the Korea Advanced Institute of Science and Technology, they studied these proteins in bacteria and found structural analogies to the human complex.

The findings have now been published in the journal Nature Structural & Molecular Biology.

In each cell about two meters of DNA must fit into a cell nucleus that has a diameter of only a few thousandths of a millimeter. There the DNA is organized in individual chromosomes in the form of very long filaments. If they are not equally and accurately distributed to the daughter cells during cell division, this can result in cancer or genetic defects such as trisomy 21. Therefore, to ensure safe transport of DNA during cell division the long and coiled DNA fibers must be tightly packed.

Scientists have only a sketchy understanding of this step. The SMC-kleisin protein complexes play a key role in this process. They consist of two arms (SMC) and a bridge (kleisin). The arms wrap around the DNA like a ring and thus can connect duplicated chromosomes or two distant parts of the same chromosome with each other.

Learning from bacteria Simple organisms like bacteria also use this method of DNA packaging. The scientists, in collaboration with colleagues from South Korea, have now elucidated the structure of a precursor of human SMC-kleisin complexes of the bacterium Bacillus subtilis. The researchers showed that the bacterial SMC-kleisin complex has two arms made of identical SMC proteins that form a ring. The arms differ in their function only through the different ends of the kleisin protein with which they are connected.

In humans the DNA packaging machinery is similarly organized. "We suspect that this asymmetric structure plays an important role in the opening and closing of the ring around the DNA," explains Frank Bürmann, PhD student in the research group 'Chromosome Organization and Dynamics' of Stephan Gruber. In addition, the scientists discovered how the ends of the kleisin can distinguish between correct and wrong binding sites on one pair of arms.

The cohesion of chromosomes is of critical importance for reproduction as well. In human eggs this cohesion must be maintained for decades to ensure error-free meiosis of the egg cell. Failure of cohesion is a likely cause for decreased fertility due to age or the occurrence of genetic defects such as trisomy 21. "The elucidation of the structure of SMC-kleisin protein complexes is an important milestone in understanding the intricate organization of chromosomes," says group leader Stephan Gruber.


Story Source:

The above story is based on materials provided by Max Planck Institute of Biochemistry. Note: Materials may be edited for content and length.


Journal Reference:

  1. Frank Bürmann, Ho-Chul Shin, Jérôme Basquin, Young-Min Soh, Victor Giménez-Oya, Yeon-Gil Kim, Byung-Ha Oh, Stephan Gruber. An asymmetric SMC–kleisin bridge in prokaryotic condensin. Nature Structural & Molecular Biology, 2013; DOI: 10.1038/nsmb.2488

Cite This Page:

Max Planck Institute of Biochemistry. "What holds chromosomes together? Structure of DNA-packaging proteins described." ScienceDaily. ScienceDaily, 28 January 2013. <www.sciencedaily.com/releases/2013/01/130128081522.htm>.
Max Planck Institute of Biochemistry. (2013, January 28). What holds chromosomes together? Structure of DNA-packaging proteins described. ScienceDaily. Retrieved April 16, 2014 from www.sciencedaily.com/releases/2013/01/130128081522.htm
Max Planck Institute of Biochemistry. "What holds chromosomes together? Structure of DNA-packaging proteins described." ScienceDaily. www.sciencedaily.com/releases/2013/01/130128081522.htm (accessed April 16, 2014).

Share This



More Plants & Animals News

Wednesday, April 16, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) — A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. Video provided by Newsy
Powered by NewsLook.com
Ebola Outbreak Now Linked To 121 Deaths

Ebola Outbreak Now Linked To 121 Deaths

Newsy (Apr. 15, 2014) — The ebola virus outbreak in West Africa is now linked to 121 deaths. Health officials fear the virus will continue to spread in urban areas. Video provided by Newsy
Powered by NewsLook.com
In Washington, a Push to Sterilize Stray Cats

In Washington, a Push to Sterilize Stray Cats

AFP (Apr. 14, 2014) — To curb the growing numbers of feral cats in the US capital, the Washington Humane Society is encouraging residents to set traps and bring the animals to a sterilization clinic, after which they are released.. Duration: 02:29 Video provided by AFP
Powered by NewsLook.com
After Attack, Officials Kill 5 Bears in Florida

After Attack, Officials Kill 5 Bears in Florida

AP (Apr. 14, 2014) — Florida wildlife officials say they have killed five bears following an attack on a woman in a suburban subdivision in central Florida. Forty-five year-old Terri Frana was attacked by a large bear in her driveway Saturday. (April 14) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins