Histone proteins are the proteins that package DNA into chromosomes. Every time the cell replicates its DNA it must make large amounts of newly made histones to organize DNA within the nucleus.
An imbalance in the production of DNA and histones is usually lethal for the cell, which is why the levels of the messenger RNA (mRNA) encoding the histone proteins must be tightly controlled to ensure the proper amounts of histones (not too many and not too few) are made.
In a collaborative effort published online in the January 18, 2013 issue of the journal Science, researchers at the University of North Carolina and Columbia University show for the first time how two key proteins in messenger RNA communicate via a molecular twist to help maintain the balance of histones to DNA.
"This is one of the safeguards that our cells have evolved and it is part of the normal progression through cell division – all growing cells have to use this all of the time," said study co-author William F. Marzluff, PhD, Kenan Distinguished Professor of biochemistry and biophysics at UNC's School of Medicine.
Every time a cell divides, Marzluff adds, it has to replicate both DNA and histone proteins and then package them together into chromosomes. "That way, each of the two cells resulting from division has one complete set of genes."
In humans, the 23 chromosomes that house roughly 35,000 genes are made up of both DNA and histone proteins. The DNA for a histone protein is first transcribed into RNA, which then acts as a guide for building a histone protein. Because the RNA relays a message – in this case a blueprint for a histone protein, it is referred to as messenger RNA, or mRNA.
Histone mRNAs differ from all other mRNAs and end in a stem-loop [or hairpin] sequence that is required for proper regulation of histone mRNAs. In this study, the Columbia team of Liang Tong, PhD, Professor of biological sciences and the corresponding author on this project, and graduate student Dazhi Tan used crystallography to reveal the structure of two important proteins near the end of the histone mRNA stem-loop. This molecular complex is required for regulating the levels of the histone mRNA.
One of these proteins, stem-loop binding protein (SLBP) is required for translation of histone mRNA into protein, and the other is an exonuclease, which is required to destroy the mRNA. Both were initially identified at UNC by Marzluff and colleague Zbigniew Dominski, PhD, Professor of biochemistry and biophysics, also a study co-author.
"We knew there was some interaction between SLBP and the exonuclease, so we asked Liang to explain how they bind and communicate," Dominski said. "And the surprising thing was that the proteins do it not by binding to each other but by changing the RNA structure at the site."
"From the science point of view, that was the most dramatic thing," Marzluff said. "The way these proteins help each other is either one can twist the RNA so the other can recognize it easier, and they don't have to touch each other to do that."
This protein complex is a critical regulator of histone synthesis, and is an important component of cell growth, he adds. "Interfering with it could provide a new method for interfering with cancer cell growth."
University of North Carolina Health Care: http://www.med.unc.edu
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
Pigs ‘edited’ with a warthog gene to resist African swine fever could help spawn GM animal farms in the UK
Mouse House to make naturalist biopic, six years after box-office failure of Creation, starring Paul Bettany
International team spends 10 years making inroads into treatment of bacterium which kills up to half of those it infects
You may not know it, but you probably have some Neanderthal in you. For people around the world, except sub-Saharan Africans, about 1 to 3 percent of their DNA comes from Neanderthals, our close cousins who disappeared roughly 39,000 years ago.
Research at Yale plotted what happened in the brains of two scientists as they held a conversation
From medicines to jet fuel, we have so many reasons to celebrate the microbes we live with every day
Genome sequencing indicates Kennewick Man is Native American, reopening the bitter battle over whether he should be reburied or studied
In the article on the discovery of dinosaurs (They’re back, Review, 6 June) you state: “In Sussex, a local doctor uncovered fragmentary remains of what appeared to be two more species of colossal extinct land reptiles.” You grossly underplay the contribution of Lewes-born Gideon Mantell, geologist and palaeontologist, author and diarist, friend to princes and international scholars as well as local doctor. Mantell not only discovered (aided by his wife) the first remains of the iguanodon in 1824 but named it – as it resembled the tooth of an iguana. This was the first known land dinosaur, Mary Anning having identified the first sea-living dinosaur.Mantell went on to put together more pieces of the jigsaw with extra fossil discoveries. In contrast to Richard Owen, whose models form the basis for the Crystal Palace dinosaurs, Mantell stated correctly that iguanodon would have walked on their back legs, using their forearms to fight or gather food. He did, however, attribute the thumb spike to a nose horn though later corrected this assumption. The Natural History Museum has a display on Gideon and his wife Mary’s contribution as well as the large “Mantell-piece” of Iguanodon fossils that he had on show in his museum in Brighton. He sold it, along with many more priceless items, to the British Museum in 1838. Gideon Mantell’s reputation deserves better than your throwaway remark. Debby MatthewsLewes, East Sussex Continue reading...
Unique triangular hairs help keep Saharan silver ants cool at 70°C by manipulating the physics of light
Most animals wouldn't confront a fearsome predator like a lion. But through sophisticated group work, hyenas launch successful raids