Figure 11.

The hypothetical mechanism of homologous exchange catalyzed by RecA, proposed in [87,88]. The binding of ss DNA and the formation of a filament is accompanied by the formation of contacts of the Tyr and Arg RecA residues of the protein with one of the bases of DNA (A–C). Subsequent binding of the duplex by the RecA-ss DNA complex and the search for homology is provided due to the formation of specific hydrogen bonds during the formation of the R-DNA triplex. In this case, the RecA protein can catalyze the destruction of Watson–Crick bonds in the duplex due to a shift in the amino–imine equilibrium after the formation of contacts from the one of base with the amino acid residue of the DNA recognition center RecA. The destruction of hydrogen bonds in the original duplex leads to the formation of new ds DNA. The impossibility of hydrogen bonding is indicated using (★). Tyr and Arg are used in the model as the most appropriate amino acid residues for this role.