If you've ever tried folding a map, packing an overnight bag or coiling a string of holiday lights, you know that the way you arrange an object affects how much space it takes up and how easy it is to use in the future. This same principle is true of DNA.
As a recent article in Science News explains, the way a DNA double helix is folded, packed and coiled is known to have a big effect on how much space it requires and how easy it is to access the information stored within. But, until recently, researchers lacked the technology to fully explore these four-dimensional DNA structures.
Now, new technology and last year's launch of the National Institutes of Health's five-year, $120 million, 4D Nucleome project is helping researchers reveal the complex architecture of DNA. William Greenleaf, PhD, assistant professor of genetics at Stanford, discusses the significance of a genome's arrangement in the Science News article:
Like the genetic text within it, the genome’s shape holds specific instructions. “The way it’s compacted forms this sort of physical memory of what the cell should be doing,” Greenleaf says.
Loops of DNA that aren’t needed by a particular cell are tucked away from the biological machinery that reads genetic blueprints, leaving only relevant genes accessible to produce proteins. Studies have shown that sections of the genome that are shoved toward the edges of a nucleus are often read less than centrally located DNA. Such specialized arrangements allow cells as diverse as brain cells, skin cells and immune cells to perform different jobs, even though each contains the same genome. “In different cell types, there are very large changes to the regions that are being used,” Greenleaf says.
Much more remains to be understood about how a genome’s shape directs its activity. Future maps might zero in on functionally interesting regions of the genome, Greenleaf says. But he cautions there is also a benefit to unbiased, general exploration. Focusing on one location in the nucleome might lead researchers to miss important structural information elsewhere, he says.
Previously: DNA origami: How our genomes fold, Packed and ready to go: The link between DNA folding and disease and DNA architecture fascinates Stanford researcher – and dictates biological outcomes
Photo by: Kate Ter Haar