Comparative and functional genomics of DNA methyltransferases in bacteria

DNA methyltransferases are best known as components of restriction-modification (R-M) systems. These serve as a form of immune response for bacteria against incoming DNA. However, these are also selfish elements acting akin to toxin-antitoxin systems. In addition, there are also solitary methyltransferases, which are not associated with restriction enzymes. These may have core regulatory functions, as best studied for the Dam methylase in E. coli; and / or they may confer protection against parasitism by R-M systems, as demonstrated for the Dcm methylase in E. coli. Here I will talk about a comparative genomics survey investigating the balance between the occurrences of DNA methyltransferases as solitary or R-M systems. I will finally present a discussion on the role of the DNA cytosine methyltransferase in regulating gene expression in E. coli.