Gene silencing in budding yeast

Published on October 1, 2007 Updated on August 31, 2016   51 min

Other Talks in the Series: Epigenetics

Hello, I'm Susan Gasser. And I'm going to you speak to you today about Gene Silencing in Budding Yeast.
Gene silencing is an epigenetic phenomenon whereby a gene is silenced or not transcribed in a manner that is heritable from one cell to the next. In the lower right-hand corner, you see colonies of yeast where a gene that will turn the yeast cell red is either expressed or not expressed in these colonies. The sectoring shows heritable repression. The same phenomenon occurs in the eye of the Drosophila when a gene is transferred or emplaced near centromeric head or chromatin. Today, I'll explain how this phenomenon occurs.
First of all, our genome is made-up of DNA complexed with histone proteins in a complex called chromatin. This protein DNA complex carries an additional level of organization and information in an epigenome. When the histone tails are acetylated or transcription factors are bound, we call this euchromatin, it's accessible and plastic to transcription machinery and usually transcriptionally active. On the other hand, if the histone tails are methylated, the other proteins bind, turning this chromatin into heterochromatin. It is inaccessible. It shows restricted expression and can be inherited in a silent state.