Final answer:
Histone methyltransferases add methyl groups to histones affecting gene expression, while histone demethylases remove these groups, reversing the effects. This dynamic process of methylation and demethylation is vital to gene regulation through chromatin remodeling.
Step-by-step explanation:
Histone methyltransferases are enzymes that add methyl groups to the lysine and arginine residues of histone proteins, leading to changes in chromatin structure and gene expression. This methylation can either repress or activate transcription depending on the specific residues that are modified. Histone demethylases, on the other hand, remove these methyl groups, reversing the methylation effects and altering gene expression accordingly. The intricate balance between methylation and demethylation plays a crucial role in epigenetic regulation of genes.
Role in Chromatin Remodeling
The modifications made by histone methyltransferases and demethylases are part of chromatin remodeling, which determines whether a gene is accessible for transcription. During chromatin remodeling, DNA becomes either more tightly wound around histones or more relaxed, influencing whether transcription factors can access and bind to the DNA. Such epigenetic changes are critical for normal development, cellular differentiation, and the body's response to environmental signals. However, disruptions in these processes can lead to diseases such as cancer.