How do histone deacetylases (HDACs) affect chromatin structure?

How do histone deacetylases (HDACs) affect chromatin structure?

• A. They promote transcription by loosening DNA
• B. They increase DNA condensation and inhibit transcription
• C. They have no effect on transcriptional activity
• D. They assist in replication by facilitating DNA unwinding

Answer: (B)

Histone deacetylases (HDACs) play a significant role in the regulation of gene expression by modifying chromatin structure. They remove acetyl groups from the lysine residues on histone proteins, which leads to a more compact and tightly coiled chromatin structure. This increased condensation of chromatin makes the DNA less accessible to the transcriptional machinery, effectively inhibiting transcription. The tighter packing of DNA prevents the binding of transcription factors and RNA polymerase, which are essential for the initiation of transcription. Consequently, the primary effect of HDACs is to suppress gene expression by promoting this condensed configuration of chromatin.

Histone deacetylases (HDACs) play a significant role in the regulation of gene expression by modifying chromatin structure. They remove acetyl groups from the lysine residues on histone proteins, which leads to a more compact and tightly coiled chromatin structure. This increased condensation of chromatin makes the DNA less accessible to the transcriptional machinery, effectively inhibiting transcription. The tighter packing of DNA prevents the binding of transcription factors and RNA polymerase, which are essential for the initiation of transcription. Consequently, the primary effect of HDACs is to suppress gene expression by promoting this condensed configuration of chromatin.