Scientists reveal structure of gateways to gene control ( isely map their positions across the en...)

Scientists reveal structure of gateways to gene control

isely map their positions across the entire genome," explains Schuster. The map reveals, for the first time, precisely which DNA sequences are part of the control-center's H2A.Z nucleosome for each gene in the yeast genome. Also for the first time, researchers now have a clear picture of how H2A.Z nucleosomes help to control whether or not a gene can be turned on.

Another discovery is that transcription-control centers tend to be located on the outside edge of the nucleosome and tend to face outward on the DNA helix, allowing the cell's transcription proteins to find them more easily. "This arrangement makes sense, because when signaling proteins arrive at a control center they are well situated to help push the nucleosome out of the way so the reading of the gene can begin," Pugh said.

"Previous research had indicated that DNA sequences located upstream of a gene might be a region that controls whether that gene is read or not, but we did not know the architecture of those sequences -- whether they were exposed and therefore ready for work. Now we know that the gateway to transcription is a part of this control region and that the nucleosome keeps it locked so the gene cannot be turned on until it is needed," Pugh said. When the gene is needed, the cell's molecular machinery loosens the DNA wrapping around the nucleosome, unlocking the transcription gateway to give access to the cell's molecular transcription machinery. "We think that the function of the nucleosome is to control the gateway to transcription," Pugh said.

The research reveals how the pieces of DNA that regulate genes at the transcription-promoter sites are packaged on nucleosomes. The knowledge that these sites are located on the outside edge of the nucleosome spool will help to focus research designed to manipulate gene expression. "Our study has provided a much clearer picture of the architecture of the DNA in the control regions, allowing us to understand much
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Source:Penn State

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( isely map their positions across the en...)Scientists reveal structure of gateways to gene control