The study reveling that protein maintaining a delicate balance of tightly packing DNA inside yeast cells with the same genetic material; while also allowing for variation amongst them.
The incredibly long strands of DNA found in cells; are packing into a structure called chromatin with the help of proteins called histones. But heterochromatin is where parts of chromatin are really tightly packing together. This makes certain genes difficult to access; effectively silencing them.
As the abnormal heterochromatin formation can inhibit genes that are essential for basic cell functions. But it can also play a role in cellular adaptation to changing circumstances by modifying gene accessibility.However, the mechanisms that regulating heterochromatin distribution are not yet fully understood.
Protein balance in DNA
A protein, calling Epe1, is knowing for its suppressive role in the formation of heterochromatin. When a fission yeast cell divides into two; each cell has identical genetic material. The study finding that turning off Epe1 in yeast cells led to stochastic heterochromatin formation.
Altering the characteristics of some cells and leading to the production of a more diverse yeast population. It also promotes the removal of H3K9me on already-formed ectopic heterochromatin, destabilizing the tight structure. Interestingly, the study showing that the removal of ectopic heterochromatin by Epe1 is incomplete.
At the molecular level, Epe1 works against a molecular label on histone called H3K9me which recruits gene-silencing proteins for heterochromatin formation. The team found that Epe1 prevents H3K9me deposition at sites where abnormal “ectopic” heterochromatin has the potential to form. It also promotes the removal of H3K9me on already-formed ectopic heterochromatin, destabilizing the tight structure.
Interestingly, the study showing that the removal of ectopic heterochromatin by Epe1 is incomplete. Thus, it creates diversity in gene expression and cell characteristics in a population with the same genetic material; while Epe1 prevents the emergence of extreme diversity caused by accidental heterochromatin formation, it also allows individuality. Cell diversity is thought to help adaptation to ever-changing environments, but, it is not always a good thing.