Microbacteria offer protection against the penetration of foreign DNA with not only RMS, but also the DISARM and BREX systems [1, 2]. RMS consists of 2 or 3 genes, while DISARM and BREX systems contain 5-6 genes. We report on the discovery of the mesophilic Microbacterium sp. Gd 4-13 taken from permafrost soils dating back 34,400 years. The study of this bacterium has garnered interest due to the presence of a endonuclease restriction (ERse) and DNA-methyltransferase genes (MTse). The endonuclease restriction is currently the only one that recognizes the site at the 5´-GCCGG↓C with the 3´overhanging end.

An analysis of the flanking region of the RMS of MspGI was carried out to detect the cassette composition of RMS MspGI genes similar to DISARM or BREX. Thus, three short ORFs are located upstream of the MTse gene in the region of ~3.5 kb and their function is unknown. Downstream of the ERse gene is the HNH ENse gene, followed by hp and recombinase (Fig. 2) [5].
Thus, an analysis of the flanking region RMS MspGI showed the presence of the helicase and HNH endonuclease genes. The presence of MTse and ERse, as well as the fact that these genes are part of the DISARM gene cassette, could suggest that although RMS MspGI does not belong to the DISARM or BREX systems, the flanking genes may be involved in protecting the cell from the penetration of foreign DNA in vivo in the complex with RMS MspGI genes.