A novel strategy to protect prokaryotic cells from virus infection.

The recent discovery of the CRISPR-Cas-mediated acquired immunity system highlights the fact that our knowledge of phage/virus defense mechanisms encoded in bacterial and archaeal genomes is far from complete. Indeed, new prokaryotic immune systems are now continually being discovered. A recent report described a novel glycosylase that recognizes α-glycosyl-hydroxymethyl cytosin (α-Glu-hmC), a modified base observed in the T4 phage genome, where it produces an abasic site, thereby inhibiting the phage propagation.