HMT

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Introductions

Histone Methyltransferases are an important class of enzymes whose presence greatly regulates and influences the level of gene expression. They can affect the biological function of histones and thus gene expression, which in turn affects cell growth and development. Histone methyltransferases are a class of catalytic enzymes that transfer methyl groups to the nitrogen residues of histones. The histone methyltransferases are catalytic enzymes that transfer methyl groups to the nitrogen residues of histones, thereby changing the conformation of the histones and causing changes in gene expression. Its role is spread over many aspects of the genome, such as affecting gene transcriptional activity in open chromatin and protecting genes from environmental influences in closed chromatin.

Classifications

Histone methyltransferases are divided into two major groups: non-structural histone methyltransferases, which are able to transfer methyl groups to structural histones, thereby affecting cell development and gene expression; and structural histone methyltransferases, which are able to transfer methyl groups to structural histones, thereby affecting the cellular response to the external environment.

Functions

Histone methyltransferases occupy an important position in biological processes. They can promote cell differentiation, proliferation, repair and death, as well as the regulation of cell development and function, thus affecting cell structure and function. Also, histone methyltransferases can regulate cellular DNA methylation levels and affect gene expression, thereby altering cellular properties and functions. In addition, histone methyltransferases can be used to regulate the genome, for drug screening and development, and for gene therapy. Histone methyltransferases have also been used in tumor therapy because they can control cellular senescence and apoptosis and mitigate tumor progression.

Catalytic mechanism

In order for the reaction to proceed, S-Adenosyl methionine (SAM) and the lysine residue of the substrate histone tail must first be bound and properly oriented in the catalytic pocket of the SET domain. Next, a nearby tyrosine residue deprotonates the ε-amino group of the lysine residue.[10] The lysine chain then makes a nucleophilic attack on the methyl group on the sulfur atom of the SAM molecule, transferring the methyl group to the lysine side chain.

Role in gene regulation

Histone methylation plays an important role in epigenetic gene regulation. Methylated histones can either repress or activate transcription as different experimental findings suggest, depending on the site of methylation. For example, it is likely that the methylation of lysine 9 on histone H3 (H3K9me3) in the promoter region of genes prevents excessive expression of these genes and, therefore, delays cell cycle transition and/or proliferation.

Summary

In conclusion, histone methyltransferases are extremely important and their action affects the level of gene expression and are important regulators of cell reproduction and development. Its regulatory role not only affects cell structure and function, but also influences the rapid cellular response to pathogens, inhibition of cancer cell growth and tumor therapy, etc. Therefore, it is important to study histone methyltransferases. In summary, histone methyltransferases are an important class of enzymes whose presence can regulate and influence the level of gene expression, promote cell differentiation, proliferation, repair and death, as well as the regulation of cell development and function, thus affecting cell structure and function. In addition, histone methyltransferases can also be used to regulate the genome, for drug screening and development, and for gene therapy. Thus, the importance of studying histone methyltransferases cannot be overstated.