<P> Acetylation has the effect of changing the overall charge of the histone tail from positive to neutral . Nucleosome formation is dependent on the positive charges of the H4 histones and the negative charge on the surface of H2A histone fold domains . Acetylation of the histone tails disrupts this association , leading to weaker binding of the nucleosomal components . By doing this , the DNA is more accessible and leads to more transcription factors being able to reach the DNA . Thus , acetylation of histones is known to increase the expression of genes through transcription activation . Deacetylation performed by HDAC molecules has the opposite effect . By deacetylating the histone tails , the DNA becomes more tightly wrapped around the histone cores , making it harder for transcription factors to bind to the DNA . This leads to decreased levels of gene expression and is known as gene silencing . </P>
<P> Acetylation has the effect of changing the overall charge of the histone tail from positive to neutral . Nucleosome formation is dependent on the positive charges of the H4 histones and the negative charge on the surface of H2A histone fold domains . Acetylation of the histone tails disrupts this association , leading to weaker binding of the nucleosomal components . By doing this , the DNA is more accessible and leads to more transcription factors being able to reach the DNA . Thus , acetylation of histones is known to increase the expression of genes through transcription activation . Deacetylation performed by HDAC molecules has the opposite effect . By deacetylating the histone tails , the DNA becomes more tightly wrapped around the histone cores , making it harder for transcription factors to bind to the DNA . This leads to decreased levels of gene expression and is known as gene silencing . </P>
what chemical changes in histone proteins are responsible for changes in gene expression
what chemical changes in histone proteins are responsible for changes in gene expression
Acetylation Deacetylation
Acetylation Deacetylation