Short Peptides Regulate Gene Expression

This work from Vladimir Khavinson's group at the St. Petersburg Institute of Bioregulation and Gerontology provided one of the few mechanistic explanations proposed for the biological activity of short bioregulatory peptides — the family of dipeptides, tripeptides, and tetrapeptides developed over decades by the Russian school of bioregulation. The focus was to demonstrate that these small molecules act as epigenetic signaling molecules, directly interacting with DNA to modulate gene transcription.

The authors built spatial models of peptide-DNA complexes by molecular docking for 19 short peptides, including EDP (Glu-Asp-Pro), the active principle of Crystagen — the immunomodulatory tripeptide derived from thymic extract. The simulations explored interactions with major and minor grooves of B-DNA, identifying preferred base sequences for each peptide.

Results established specific peptide-sequence correspondences: EDP (Crystagen) preferentially binds to the "agat" sequence in DNA, KE (Vilon) also to "agat", KEDW (Pancragen) and AED (Vesugen) to "acct", and peptides AEDL (Cortagen) and EDL to "ctcc". These interactions occur through hydrophobic contacts and hydrogen bonds between amino acid residues and nitrogenous bases, without the need for mediating proteins.

The proposed model was: short peptides cross the cell and nuclear membranes, bind to specific DNA sites, and modulate chromatin accessibility and transcription of dozens of genes involved in proliferation, differentiation, apoptosis, and protein synthesis. This work provides the structural basis for the Khavinson concept that short peptides exert broad and coordinated gene regulation, and justifies the use of EDP/Crystagen as an immunological modulator via transcriptional reprogramming in lymphocytes and thymic cells.