2Gamaleya Center of Epidemiology and Microbiology, 123098 Moscow, Russia
3Institute of Agricultural Biotechnology, 127550 Moscow, Russia
4Lomonosov Moscow State University, Faculty of Bioengineering and Bioinformatics, 119991 Moscow, Russia
5Institute of System Studies, 117281 Moscow, Russia
* To whom correspondence should be addressed.
Received July 1, 2015; Revision received July 23, 2015
Restriction–modification (R-M) systems are able to methylate or cleave DNA depending on methylation status of their recognition site. It allows them to protect bacterial cells from invasion by foreign DNA. Comparative analysis of a large number of available bacterial genomes and methylomes clearly demonstrates that the role of R-M systems in bacteria is wider than only defense. R-M systems maintain heterogeneity of a bacterial population and are involved in adaptation of bacteria to change in their environmental conditions. R-M systems can be essential for host colonization by pathogenic bacteria. Phase variation and intragenomic recombinations are sources of the fast evolution of the specificity of R-M systems. This review focuses on the influence of R-M systems on evolution and ecology of prokaryotes.
KEY WORDS: restriction–modification systems, DNA methyltransferase, restriction endonuclease, horizontal gene transfer, epigenetics, bacteria, DNA methylation