Antirestriction Proteins: Structures, Functions, and Prospects of Application

Restriction-modification (RM) systems play a crucial role in protecting prokaryotes from foreign DNA. Genes encoding antirestriction proteins such as ArdA and ArdB are often among the first genes to enter the cell upon infection. Recent studies demonstrated that DNA-mimicking ArdA proteins exhibit specificity to RM systems, meaning that they can mimic specific DNA sequences. Moreover, this specificity can be achieved using recently discovered very small DNA-mimicking proteins called sArdA. This suggests promising applications for these DNA-mimicking “almost peptides” in specifically interacting with DNA-binding proteins to regulate intracellular processes. Another class of antirestriction proteins ArdB appears to act as a universal DNA-binding agent, inhibiting restriction activity of all known type I RM systems, as well as CRISPR/Cas3. These findings could potentially enhance transformation efficiency in hard-to-transform strains.