Genome Complexity; Histone coding (Introduction)

by David Turell , Tuesday, February 10, 2015, 19:27 (3574 days ago) @ David Turell

Histones can modify or control genes. There are enzymes that work with histones. the mechanism is complex and very partially understood. DNA is wrapped tightly around histones in a nucleus.:-http://phys.org/news/2015-02-kind-tool-histone-code.html-"One aspect of gene regulation involves enzymes placing chemical tags or modifications on histone proteins - which control a cell's access to the DNA sequences that make up a gene. Properly regulated access allows cells to develop, function, and proliferate normally. The chemical modification of histones is thought to be a form of epigenetic information - information separate from our DNA - that controls gene regulation. This idea is based on the study of the enzymes that chemically modify histones. However, there is a flaw in this argument.-"In complex organisms, such as fruit flies, mice, and humans, scientists have only been able to infer how these enzymes mechanistically accomplish their tasks," said Daniel McKay, PhD, assistant professor of genetics and biology and first author of the paper. "It's been technically impossible to directly study the role of histone modifications. Now, through our collaboration between UNC biologists, we've been able to develop a tool in fruit flies to directly test the function of histones independently of the enzymes that modify them."-"Previously, in mammalian cells, other researchers had discovered that when you mutate a specific modifying enzyme, the result is death because the cells can't replicate.-"With their new fruit fly research model, the UNC researchers altered the histone gene so that this particular enzyme could not modify its histone protein target. The result was not death. In fact, the flies lived and flew as normal flies do. This meant that the enzyme, which was previously proven to be vital to life, must do something else very important.-"There must be another target for that modifying enzyme," Matera said. "There must be another hidden carrier of epigenetic information that we don't know about."-"McKay added, "This is a demonstration of the potential of our epigenetic platform. Going forward, we're going to do a lot more experiments to identify more discrepancies and hopefully other targets of these enzymes. We're on the ground floor of a long-term project."-"This research shows that the epigenetic recipe book for yeast is thin. The recipe book for humans, which is genetically akin to the one for fruit flies, is much thicker, more complex, and full of hidden ingredients scientists have yet to discover.-"Now, scientists have a tool to test the recipes."