Functional complementation between inactive fragments of M.SssI. Hin6I digestion of plasmids expressing the M.SssI fragments shown above the lanes. Protection against Hin6I digestion is a sign of C5-methylation at CG sites. Plasmids indicated by underlining were prepared from cells grown in the presence of 0.5 % arabinose. M, DNA size marker (Fermentas). Undigested and digested samples are identified by – and + signs, respectively below the lanes.