Saturday, November 14, 2015

Why some genes are highly expressed

In an interesting research analysis, the way in which nucleosomes affect gene expression was studied. Using yeast DNA, two different types of promoters were discovered. By manipulating nucleosomes, some genes can be expressed at a higher rate than others. A nucleosome is a structure of DNA wrapped around histones or proteins. When DNA is in this form, it cannot be read and therefore will not be transcribed. When nucleosomes are unbound, DNA can be transcribed into proteins. One of the mysteries to gene expression is how access to the promoter DNA is determined, which must be reached in order for DNA to be transcribed. 

The discovered promoters, each characterized by their state of nucleosome stability, contained a type of promoter that had unstable nucleosomes and led to a higher rate of gene expression. The other promoter that contained stable nucleosomes were not expressed as frequently. One of the most important findings of the study was the existence of fragile nucleosomes, labeled as such due to the fact that they do not resist as much to enzymes as other nucleosomes. These nucleosomes were associated with the promoter that high amounts of transcription. The genes with fragile nucleosomes were found to be controlled by nutrient availability. This fact captured my attention the most, as it made me wonder- is this in any way related to environmental factors? If transcription is related to nucleosomes in their willingness to unravel, which is dependent on nutrients, could gene expression be altered by what nutrients or chemicals enter the body? 

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