In silico study of HASDI (high-affinity selective DNA intercalator) as a new agent capable of highly selective recognition of the DNA sequence.

Cancer as an acquired genetic disease is based on changes both in the genome itself and in transcription processes. Accordingly, it is at the DNA level that it makes sense to search for and design agents capable of effective and selective anticancer action. In this study, we used an iterative approach based on a molecular dynamics simulation to design a highly selective DNA-intercalating agent called HASDI. To confirm its selective affinity to DNA, we conducted two simulation experiments: HASDI in a complex with a DNA fragment of the EBNA1 gene (it targets 16 nucleotide pairs of this gene) and HASDI in a complex with a random DNA fragment of the KCNH2 gene. The molecular dynamics simulation was carried out in the GROMACS 2019 package. The binding energy was calculated by gmx_MMPBSA 1.5.2. The further analysis was performed using the built-in utilities of GROMACS, gmx_MMPBSA and also XMGRACE and Pymol 1.8. As a result, we determined that the EBNA1-50nt/HASDI complex was stable throughout the whole simulation trajectory. HASDI, due to the presence of a linker modified depending on a specific pair of nitrogenous bases, formed an average of 32 hydrogen bonds with a sequence of 16 nucleotide pairs. Phenazine rings were stably intercalated every 2 base pairs. The root-mean-square deviation of HASDI in such a complex fluctuated around the value of 6.5 Å and had no tendency to increase. The calculated value of the binding free energy was - 235.3 ± 7.77 kcal/mol. The KCNH2-50nt/HASDI complex, as an example of the intercalation of the designed structure into a random part of the human genome, maintained the stability of its position at a level comparable to the EBNA1-50nt/HASDI complex. The phenazine rings were constantly intercalated in their original positions, and the root-mean-square deviation fluctuated around one value, although it had a tendency to chaotic changes. At the same time, this complex was characterized by 17-19 hydrogen bonds, on average, and the binding free energy was - 193.47 ± 14.09 kcal/mol. Moreover, the DNA duplex had local single-nucleotide melting in the region of the 4th linker. According to a significant decrease in the number of hydrogen bonds, a decrease in energy gain, as well as a decrease in the stability of the DNA duplex characteristic of the KCNH2-50nt/HASDI complex compared to the target EBNA1-50nt/HASDI complex, the molecule we designed can be considered a potentially selective DNA polyintercalating agent capable of relatively accurate recognition of 16 base pairs.