Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study finds protein is required for human chromosome production

13.10.2005


Scientists at the University of North Carolina at Chapel Hill School of Medicine have identified an elusive protein that performs a necessary step in the production of human chromosomes.

The new study appears in the most recent issue (Oct. 7) of the journal Cell.

The study found that a protein called CPSF73 acts like scissors to cut strands of histone messenger RNA (mRNA) in the cell nucleus. This cutting action produces the mRNA needed to create histone proteins that combine with DNA to form chromosomes.



Like all other proteins, histones are made when a specialized RNA molecule is "read" by ribosomes, the cell’s protein factories. The type of RNA, which relays information from the DNA (inside the nucleus) to the ribosome (outside the nucleus), is called messenger RNA.

RNA that is not cut by CPSF73 is destroyed in the nucleus and never becomes messenger RNA, said Dr. William Marzluff, senior author of the study and Kenan distinguished professor of biochemistry and biophysics in UNC’s School of Medicine.

"This cutting of histone messenger RNA takes place as growing cells prepare to divide and is absolutely necessary for their eventual division," Marzluff said. Histone proteins help organize and compact within the nucleus the 6 billion nucleotides, or DNA bases, that make up the human genome – combinations of "A’s," "T’s," "G’s" and "C’s." Without histones, cells cannot survive.

Dr. Zbigniew Dominski, associate professor of biochemistry and biophysics, has been searching for the protein that cuts histone messenger RNA since joining forces with Marzluff 10 years ago. He is the corresponding and lead author of the study.

When RNA is first made from DNA, it is premature and cannot direct the synthesis of its corresponding protein until it is processed into mature messenger RNA, which includes being cut at a specific site, Dominski said.

"This is a very complex process that requires many proteins to bind to the RNA molecule and show the cutting enzyme where to cleave the RNA," he added.

Dominski was able to duplicate, in a test tube, the histone mRNA processing that takes place normally inside a cell’s nucleus. However, the RNA cutting reaction was so quick that he was unable to determine which of the countless proteins inside the test tube was responsible.

"We set a trap by subtly changing the chemical makeup of the histone messenger RNA right where it is cut. This allows the protein to still come to the RNA but forces it to cut more slowly," Dominski said.

By slowing down the reaction, Dominski had enough time to irreversibly attach the RNA cutting protein, or nuclease, to the RNA itself using ultraviolet light as a cross-linking agent. Once attached to the RNA, the long-sought-after nuclease was trapped, allowing its subsequent identification.

The discovery that the RNA cutting protein is CPSF73 was unexpected. This protein was already connected with processing of a completely different class of messenger RNA, polyadenylated mRNAs. These messenger RNAs serve as blueprints for all proteins other than the histones. "In terms of evolution, all messenger RNAs appear to be made with the aid of the same protein, CPSF73," Marzluff said. "This suggests that the two mRNA processing mechanisms, for polyadenylated and histone mRNAs, are distantly related."

The authors further demonstrate that CPSF73 not only cuts the histone messenger RNA molecule in two, but also then chews the unneeded portion of the histone mRNA molecule into pieces. It is rare to find two such activities within a single protein, Dominski said.

"From the point of view of understanding biology, our findings provide a unified mechanism for the synthesis of all messenger RNAs," Marzluff said.

UNC School of Medicine technician and co-author Xiao-cui Yang assisted Dominski and Marzluff in this study. Their work was supported by a grant from the National Institutes of Health.

L. H. Lang | EurekAlert!
Further information:
http://www.med.unc.edu

More articles from Studies and Analyses:

nachricht Physics of bubbles could explain language patterns
25.07.2017 | University of Portsmouth

nachricht Obstructing the ‘inner eye’
07.07.2017 | Friedrich-Schiller-Universität Jena

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

CCNY physicists master unexplored electron property

26.07.2017 | Physics and Astronomy

Molecular microscopy illuminates molecular motor motion

26.07.2017 | Life Sciences

Large-Mouthed Fish Was Top Predator After Mass Extinction

26.07.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>