The genome's 3-D structure shapes how genes are expressed
Roughly 3 metres of DNA is tightly folded into the nucleus of every cell in our body. This folding allows some genes to be 'expressed', or activated, while excluding others.
Dr Tim Mercer and Professor John Mattick from Sydney's Garvan Institute of Medical Research and Professor John Stamatoyannopoulos from Seattle's University of Washington analysed the genome's 3D structure, at high resolution.
Genes are made up of 'exons' and 'introns' – the former being the sequences that code for protein and are expressed, and the latter being stretches of noncoding DNA in-between. As the genes are copied, or 'transcribed', from DNA into RNA, the intron sequences are cut or 'spliced' out and the remaining exons are strung together to form a sequence that encodes a protein. Depending on which exons are strung together, the same gene can generate different proteins.
Using vast amounts of data from the ENCODE project*, Dr Tim Mercer and colleagues have inferred the folding of the genome, finding that even within a gene, selected exons are easily exposed.
“Imagine a long and immensely convoluted grape vine, its twisted branches presenting some grapes to be plucked easily, while concealing others beyond reach,” said Dr Mercer. “At the same time, imagine a lazy fruit picker only picking the grapes within easy reach.
“The same principle applies in the genome. Specific genes and even specific exons, are placed within easy reach by folding.”
“Over the last few years, we've been starting to appreciate just how the folding of the genome helps determine how it's expressed and regulated,”
“This study provides the first indication that the three-dimensional structure of the genome can influence the splicing of genes.”
“We can infer that the genome is folded in such a way that the promoter region — the sequence that initiates transcription of a gene — is located alongside exons, and they are all presented to transcription machinery.”
“This supports a new way of looking at things, one that the genome is folded around transcription machinery, rather than the other way around. Those genes that come in contact with the transcription machinery get transcribed, while those parts which loop away are ignored.”
The National Human Genome Research Institute launched a public research consortium named ENCODE, the Encyclopedia Of DNA Elements, in September 2003, to carry out a project to identify all functional elements in the human genome sequence.
Alle Nachrichten aus der Kategorie: Life Sciences
Articles and reports from the Life Sciences area deal with applied and basic research into modern biology, chemistry and human medicine.
Valuable information can be found on a range of life sciences fields including bacteriology, biochemistry, bionics, bioinformatics, biophysics, biotechnology, genetics, geobotany, human biology, marine biology, microbiology, molecular biology, cellular biology, zoology, bioinorganic chemistry, microchemistry and environmental chemistry.
Argonne targets lithium-rich materials as key to more sustainable cost-effective batteries
Next-generation batteries using lithium-rich materials could be more sustainable and cost-effective, according to a team of researchers with the U.S. Department of Energy’s (DOE) Argonne National Laboratory. The pivotal discovery,…
Why disordered light-harvesting systems produce ordered outcomes
Scientists typically prefer to work with ordered systems. However, a diverse team of physicists and biophysicists from the University of Groningen found that individual light-harvesting nanotubes with disordered molecular structures…
RadarGlass – from vehicle headlight to radar transceiver
As a result of modern Advanced Driver Assistance Systems, the use of radar technology has become indispensable for the automotive sector. With the installation of a large and growing number…