Mechanisms used by phages to resist the action of restriction endonucleases.
This is other than the infrequent epigenetic modifications of the phage DNA such that it is recognized, essentially, as bacterial self DNA rather than as foreign DNA. It is also other than having genomes that do not possess restriction enzyme recognition sequences, though that also serves phages as a means of avoiding restriction by restriction endonucleases.
Antirestriction mechanisms are mediated by phage gene products that act either during the synthesis step of infections, thereby effecting antirestriction during the following infection (particularly by modifying phage DNA), or involve processes by which restriction endonucleases are more actively thwarted during the infection process prior to nucleic acid replication and virion assembly.
There thus are four basic mechanisms by which restriction by restriction endonucleases can be avoided: (1) mutational elimination of recognition sequences, (2) obscurance of recognition sequences through phage-mediated DNA modification, (3) interfere with the action of endonucleases but prior to enzyme-DNA interaction, and (4) by chance bacteria-mediated modification of phage DNA prior to restriction by the same bacterium’s restriction endonuclease enzymes.
For more on this topic, see Wikipedia, Google, and PubMed. Contact web master. Return to terms.