Featured Research

from universities, journals, and other organizations

Protein Discovery Tied To DNA Master Switch

Date:
December 21, 2001
Source:
University Of North Carolina School Of Medicine
Summary:
A new cellular protein discovered by scientists at the University of North Carolina at Chapel Hill appears to be a crucial molecular component of a master switch that turns genes on and off.

CHAPEL HILL - A new cellular protein discovered by scientists at the University of North Carolina at Chapel Hill appears to be a crucial molecular component of a master switch that turns genes on and off.

The new molecule may prove critical to the regulation of gene expression. If so, it could eventually lead to new treatments for diseases and provide information vital to research aimed at using stem cells to generate organs.

The discovery of the new molecule, SET7, was headed by Dr. Yi Zhang, assistant professor of biochemistry at UNC-CH School of Medicine and a member of the UNC Lineberger Comprehensive Cancer Center. A report of the research is published in the December 21 issue of the journal Molecular Cell.

All gene expression must be tightly controlled, Zhang said. "When we talk about genes, we're talking about DNA in the cell nucleus that's complexed with several basic proteins called histones. The basic structure is like 'beads on a string' which can be further packaged into a high order structure called chromatin," he explained.

"This chromatin packaging allows for efficient storage of genetic information. But it also impedes access to DNA by transcription factors, proteins that regulate gene expression."

Zhang and his colleagues believe their discovery to be part of the mechanism that dynamically changes the chromatin structure, its loosening or tightening. They focused their attention on a particular covalent modification -- methylation, addition of a methyl group to lysine, one of the amino acids that comprise the tail domain of the histone molecules.

Why lysine? Because recent research had linked gene silencing, or deactivation, to methylation of a particular lysine site (lysine 9) on the tail of the histone H3.

As it turns out, modifications of amino acids by methylation mainly occur on lysine. "We've known for three decades that histone can be methylated, but nobody knew the identity of the enzymes responsible for this modification until a year ago when the first lysine 9-specific histone methyltransferase was identified," Zhang said. "The new enzyme we identified, SET7, specifically modifies lysine 4, a different residue on the histone H3 N-terminal tail. It's the first protein ever identified from higher eukaryotes [including all mammals] that methylates histone H3 at lysine 4."

"By methylating H3-lysine 4, SET7 makes the chromatin structure more open, so other proteins can access the gene." The study team also determined that methylation of histone H3 at lysine 4 and lysine 9 inhibit each other. Thus, the findings suggest that methylation of either lysine 4 or 9 could determine gene activation or silencing.

Still, the situation is more complex than that. Among the possibilities, SET7 could have functioning partners yet to be identified. "We know the enzyme modifies lysine 4. After it's modified, we don't know exactly how the gene turns on," Zhang said. Study co-author Dr. Christoph Borchers, assistant professor of biochemistry at the medical school, used mass spectrometry to help identify the protein by measuring the atomic masses of its fragments.

Zhang is currently studying the possible importance of SET7 in embryogenesis, development at the very beginnings of life.

The research was supported with funds from the National Institute of General Medicine at NIH and the American Cancer Society. Zhang's UNC co-authors along with Borchers are Dr. Hengbin Wang; Ru Cao, doctoral student; Li Xia, technician. Drs. Hdiye Erdjument-Bromage and Paul Tempest were co-authors from Memorial Sloan Kettering Cancer Center in New York.


Story Source:

The above story is based on materials provided by University Of North Carolina School Of Medicine. Note: Materials may be edited for content and length.


Cite This Page:

University Of North Carolina School Of Medicine. "Protein Discovery Tied To DNA Master Switch." ScienceDaily. ScienceDaily, 21 December 2001. <www.sciencedaily.com/releases/2001/12/011221081457.htm>.
University Of North Carolina School Of Medicine. (2001, December 21). Protein Discovery Tied To DNA Master Switch. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2001/12/011221081457.htm
University Of North Carolina School Of Medicine. "Protein Discovery Tied To DNA Master Switch." ScienceDaily. www.sciencedaily.com/releases/2001/12/011221081457.htm (accessed July 22, 2014).

Share This




More Health & Medicine News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

TheStreet (July 21, 2014) New research shows Gilead Science's drug Sovaldi helps in curing hepatitis C in those who suffer from HIV. In a medical study, the combination of Gilead's Hep C drug with anti-viral drug Ribavirin cured 76% of HIV-positive patients suffering from the most common hepatitis C strain. Hepatitis C and related complications have been a top cause of death in HIV-positive patients. Typical medication used to treat the disease, including interferon proteins, tended to react badly with HIV drugs. However, Sovaldi's %1,000-a-pill price tag could limit the number of patients able to access the treatment. TheStreet's Keris Lahiff reports from New York. Video provided by TheStreet
Powered by NewsLook.com
$23.6 Billion Awarded To Widow In Smoking Lawsuit

$23.6 Billion Awarded To Widow In Smoking Lawsuit

Newsy (July 20, 2014) Cynthia Robinson claims R.J. Reynolds Tobacco Company hid the health and addiction risks of its products, leading to the death of her husband in 1996. Video provided by Newsy
Powered by NewsLook.com
Tooth Plaque Provides Insight Into Diets Of Ancient People

Tooth Plaque Provides Insight Into Diets Of Ancient People

Newsy (July 19, 2014) Research on plaque from ancient teeth shows that our prehistoric ancestor's had a detailed understanding of plants long before developing agriculture. Video provided by Newsy
Powered by NewsLook.com
Contaminated Water Kills 3 Babies in South African Town

Contaminated Water Kills 3 Babies in South African Town

AFP (July 18, 2014) Contaminated water in South Africa's northwestern town of Bloemhof kills three babies and hospitalises over 500 people. The incident highlights growing fears over water safety in South Africa. Duration: 02:22 Video provided by AFP
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