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Evolutionarily preserved mechanism governs use of genes
August 18, 2009Researchers at Uppsala University have found that the protein coding parts of a gene are packed in special nucleosomes. The same type of packaging is found in the roundworm C elegans, which is a primeval relative of humans. The mechanism can thereby be traced back a billion years in time, according to the study presented in the journal Genome Research.
Human genes are packed in nucleosomes, which contain epigenetic signals directing how the genes are to be used. The cell nucleus contains DNA, which is wound around proteins to form units called nucleosomes, not unlike pearls on a string. Genes on average contain ten protein coding units called exons. Previously there was no known correlation between nucleosomes and exons . New results show that nucleosomes are placed over exons. This means that the area containing the protein code is packed in discrete units. These results are presented by a research team at Uppsala University, led by Professor Claes Wadelius at the Department of Genetics and Pathology and Professor Jan Komorowski at the Linnaeus Centre for Bioinformatics as well as University of Warsaw.
Epigenetics is a cellular memory which identifies a cell's identity and way to respond to the environment. Epigenetic signals control genes in a flexible manner. Each genetic package, or pearl on the string, has an epigenetic signal indicating how active it is. In the present study it was shown that there is a previously undiscovered epigenetic mark on protein coding parts of the gene.
"A gene can be read in several ways and create different proteins. We have now demonstrated that there is an epigenetic control that determines which parts of the gene that are read," says Claes Wadelius.
The study is based on extremely large amounts of data published by other scientists, but not previously analyzed in such detail.
"Our findings show the value of sophisticated bioinformatic analyses and the need to delve deeper into the gigantic amounts of data from modern biological research," says Jan Komorowski.
The scientists also show that the same type of genetic packaging exists in the tiny roundworm C elegans. Humans are related to this worm through a common ancestor that lived a billion years ago. This means that the mechanism has been evolutionarily preserved during nearly one fourth of the time the earth has existed eller one fourth of earth's existence. In humans, the genetic code has been divided into smaller parts that fit into the individual packages or pearls.
"This enables a gene to be used in several different ways. This has probably contributed to human development," concludes Professor Claes Wadelius.
Uppsala University
"A gene can be read in several ways and create different proteins. We have now demonstrated that there is an epigenetic control that determines which parts of the gene that are read," says Claes Wadelius.
The study is based on extremely large amounts of data published by other scientists, but not previously analyzed in such detail.
"Our findings show the value of sophisticated bioinformatic analyses and the need to delve deeper into the gigantic amounts of data from modern biological research," says Jan Komorowski.
The scientists also show that the same type of genetic packaging exists in the tiny roundworm C elegans. Humans are related to this worm through a common ancestor that lived a billion years ago. This means that the mechanism has been evolutionarily preserved during nearly one fourth of the time the earth has existed eller one fourth of earth's existence. In humans, the genetic code has been divided into smaller parts that fit into the individual packages or pearls.
"This enables a gene to be used in several different ways. This has probably contributed to human development," concludes Professor Claes Wadelius.
Uppsala University
Nucleosomes Current Events and Nucleosomes News RSSGerton Lab determines the composition of centromeric chromatin
The Stowers Institute's Gerton Lab has provided new evidence to clarify the structure of nucleosomes containing Cse4, a centromere-specific histone protein required for proper kinetochore function, which plays a critical role in the process of mitosis. The work, conducted in yeast cells, was published in the most recent issue of Molecular Cell.
Conaway Lab uncovers function of potential cancer-causing gene product
The Stowers Institute's Conaway Lab has uncovered a previously unknown function of a gene product called Amplified in Liver Cancer 1 (Alc1), which may play a role in the onset of cancer.
'Normal' cells far from cancer give nanosignals of trouble
A new Northwestern University-led study of human colon, pancreatic and lung cells is the first to report that cancer cells and their non-cancerous cell neighbors, although quite different under the microscope, share very similar structural abnormalities on the nanoscale level.
Saved by junk DNA
VIB researchers linked to K.U.Leuven and Harvard University show that stretches of DNA previously believed to be useless 'junk' DNA play a vital role in the evolution of our genome.
Roles of DNA packaging protein revealed by Einstein scientists
Scientists at Albert Einstein College of Medicine of Yeshiva University have found that a class of chromatin proteins is crucial for maintaining the structure and function of chromosomes and the normal development of eukaryotic organisms.
Light shines for potential early cancer diagnosis technique
A team led by a Northwestern University biomedical engineer has developed a new optical technique that holds promise for minimally invasive screening methods for the early diagnosis of cancer.
Scripps Research Scientists Shed Light on How DNA Is Unwound So That Its Code Can Be Read
Researchers at The Scripps Research Institute have figured out how a macromolecular machine is able to unwind the long and twisted tangles of DNA within a cell's nucleus so that genetic information can be "read" and used to direct the synthesis of proteins, which have many specific functions in the body.
Conaway Lab Identifies Novel Mechanism for Regulation of Gene Expression
The Stowers Institute's Conaway Lab has demonstrated that an enzyme called Uch37 is kept in check when it is part of a human chromatin remodeling complex, INO80. The results were published in today's issue of Molecular Cell.
Once suspect protein found to promote DNA repair, prevent cancer
An abundant chromosomal protein that binds to damaged DNA prevents cancer development by enhancing DNA repair, researchers at The University of Texas M. D. Anderson Cancer Center report online this week in the Proceedings of the National Academies of Science.
Scientists Identify Key Roadblock to Gene Expression
A team of scientists has provided, for the first time, a detailed map of how the building blocks of chromosomes, the cellular structures that contain genes, are organized in the fruit fly Drosophila melanogaster.
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Repair of UV lesions in nucleosomes - intrinsic properties and remodeling [An article from: DNA Repair] by F. Thoma (Author) This digital document is a journal article from DNA Repair, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: Nucleotide excision repair and reversal of pyrimidine dimers by photolyase (photoreactivation) are two major pathways to remove UV-lesions from DNA. Here, it is discussed how lesions are recognized and removed when the DNA is condensed into nucleosomes. During the recent years it was shown that nucleosomes inhibit photolyase and excision repair in vitro and slow down repair in vivo. The correlation of DNA-repair rates with nucleosome positions in yeast suggests that intrinsic properties of nucleosomes such as mobility and... |
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Abstracts of papers presented at the 2004 collegiate meetings.: An article from: Journal of the Tennessee Academy of Science by Tennessee Academy of Science (Publisher) This digital document is an article from Journal of the Tennessee Academy of Science, published by Tennessee Academy of Science on July 1, 2004. The length of the article is 7339 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser. Citation Details Title: Abstracts of papers presented at the 2004 collegiate meetings. Publication: Journal of the Tennessee Academy of Science (Refereed) Date: July 1, 2004 Publisher: Tennessee Academy of Science Volume: 79 Issue: 3 Page: 70(8) Distributed by Thomson... | |
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Nucleosomal structure of undamaged DNA regions suppresses the non-specific DNA binding of the XPC complex [An article from: DNA Repair] by T. Yasuda (Author), K. Sugasawa (Author), Y. Shimizu (Author), S. Iwai (Author), Shiom (Author) This digital document is a journal article from DNA Repair, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: The XPC protein complex is a DNA damage detector of human nucleotide excision repair (NER). Although the XPC complex specifically binds to certain damaged sites, it also binds to undamaged DNA in a non-specific manner. The addition of a large excess of undamaged naked DNA competitively inhibited the specific binding of the XPC complex to (6-4) photoproducts and the NER dual incision step in cell-free extracts. In contrast, the addition of undamaged nucleosomal DNA as a competitor suppressed both of these inhibitory... |
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Nucleotide excision repair in chromatin and the right of entry [An article from: DNA Repair] by F. Gong (Author), Y. Kwon (Author), M.J. Smerdon (Author) This digital document is a journal article from DNA Repair, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: DNA is packaged with histones and other accessory proteins into chromatin in eukaryotic cells. It is well established that the assembly of DNA into chromatin affects induction of DNA damage as well as repair of the damage. How the DNA repair machinery detects a lesion and 'fixes it' in chromatin has been an intriguing question since the dawn of understanding DNA packaging in chromatin. Direct recognition/binding by damaged DNA binding proteins is one obvious tactic to detect a lesion. Rearrangement of chromatin structure... |
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