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 Researchers simplify tiny structures' construction drip by drip
12.11.2018 | Princeton University, Engineering School

nachricht Mandibular movement monitoring may help improve oral sleep apnea devices
06.11.2018 | Elsevier

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: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

Im Focus: Coping with errors in the quantum age

Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly

The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Epoxy compound gets a graphene bump

14.11.2018 | Materials Sciences

Microgel powder fights infection and helps wounds heal

14.11.2018 | Health and Medicine

How algae and carbon fibers could sustainably reduce the athmospheric carbon dioxide concentration

14.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>