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Biologists' discovery may force revision of biology textbooks: Novel chromatin particle halfway between DNA and a nucleosome

Date:
August 18, 2011
Source:
University of California - San Diego
Summary:
Basic biology textbooks may need a bit of revising now that biologists have discovered a never-before-noticed component of our basic genetic material.

Biologists have discovered a novel chromatin particle halfway between DNA and a nucleosome. While it looks like a nucleosome, it is in fact a distinct particle of its own, researchers say.
Credit: James Kadonaga, UC San Diego

Basic biology textbooks may need a bit of revising now that biologists at UC San Diego have discovered a never-before-noticed component of our basic genetic material.

According to the textbooks, chromatin, the natural state of DNA in the cell, is made up of nucleosomes. And nucleosomes are the basic repeating unit of chromatin.

When viewed by a high powered microscope, nucleosomes look like beads on a string. But in the Aug. 19 issue of the journal Molecular Cell, UC San Diego biologists report their discovery of a novel chromatin particle halfway between DNA and a nucleosome. While it looks like a nucleosome, they say, it is in fact a distinct particle of its own.

"This novel particle was found as a precursor to a nucleosome," said James Kadonaga, a professor of biology at UC San Diego who headed the research team and calls the particle a "pre-nucleosome." "These findings suggest that it is necessary to reconsider what chromatin is. The pre-nucleosome is likely to be an important player in how our genetic material is duplicated and used."

The biologists say that while the pre-nucleosome may look something like a nucleosome under the microscope, biochemical tests have shown that it is in reality halfway between DNA and a nucleosome.

These pre-nucleosomes, the researchers say, are converted into nucleosomes by a motor protein that uses the energy molecule ATP.

"The discovery of pre-nucleosomes suggests that much of chromatin, which has been generally presumed to consist only of nucleosomes, may be a mixture of nucleosomes and pre-nucleosomes," said Kadonaga. "So, this discovery may be the beginning of a revolution in our understanding of what chromatin is."

"The packaging of DNA with histone proteins to form chromatin helps stabilize chromosomes and plays an important role in regulating gene activities and DNA replication," said Anthony Carter, who oversees chromatin grants at the National Institute of General Medical Sciences of the National Institutes of Health, which funded the research. "The discovery of a novel intermediate DNA-histone complex offers intriguing insights into the nature of chromatin and may help us better understand how it impacts these key cellular processes."


Story Source:

The above story is based on materials provided by University of California - San Diego. The original article was written by Kim McDonald. Note: Materials may be edited for content and length.


Journal Reference:

  1. Sharon E. Torigoe, Debra L. Urwin, Haruhiko Ishii, Douglas E. Smith, James T. Kadonaga. Identification of a Rapidly Formed Nonnucleosomal Histone-DNA Intermediate that Is Converted into Chromatin by ACF. Molecular Cell, 2011; 43 (4): 638-648 DOI: 10.1016/j.molcel.2011.07.017

Cite This Page:

University of California - San Diego. "Biologists' discovery may force revision of biology textbooks: Novel chromatin particle halfway between DNA and a nucleosome." ScienceDaily. ScienceDaily, 18 August 2011. <www.sciencedaily.com/releases/2011/08/110818142842.htm>.
University of California - San Diego. (2011, August 18). Biologists' discovery may force revision of biology textbooks: Novel chromatin particle halfway between DNA and a nucleosome. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2011/08/110818142842.htm
University of California - San Diego. "Biologists' discovery may force revision of biology textbooks: Novel chromatin particle halfway between DNA and a nucleosome." ScienceDaily. www.sciencedaily.com/releases/2011/08/110818142842.htm (accessed July 25, 2014).

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