Regulation of DNA methyltransferase gene expression by short peptides in nicotiana tabacum regenerants

Abstract

Methylation of cytosine DNA residues is the most studied and stable of all epigenetic modifications. Methylation of eukaryotic DNA is carried out by DNA methyltransferases. DNA methylation is an active mechanism for controlling gene transcription and is usually associated with prolonged silencing of DNA. The effect of peptides AEDG and AEDL on the growth of calluses of tobacco (<i>Nicotiana tabacum</i>) at low concentrations (10⁻⁷ M) is similar to the effect of phytohormones, has a regulatory character, and is possibly epigenetic in nature. Peptides increase the expression of DNA methyltransferase genes. One of the possible mechanisms of regulation of DNA methyltransferase genes by AEDG and AEDL is their ability to bind to free DNA regions at certain CNG sites, which are also methylation sites of plant cytosine methyltransferases. The AEDG peptide preferably binds to the CAG site and the AEDL peptide to the CTG site. By binding to the same sites as DNA methyltransferase, peptides block methylation sites, thereby reducing the level of DNA methylation. The specific binding of peptides to different sites that we discovered can be of great importance in gene regulation, since peptides with different structures can block different DNA regions for methylation of certain genes, thereby activating or silencing their expression.