Targeted DNA Methylation Using an Artificially Bisected M.HhaI Fused to Zinc Fingers
Methylation was assessed as in Figure 2. In this experiment, the C-terminal fragment of M.HhaI is truncated by 6 amino acids, X = 3, Y = 1, and Z = 0. Methyltransferase activity was assessed with and without target sites present. Moving the target site from site 1 to site 2 did not have a large effect on activity. Target half sites (in which either the HS1 or HS2 binding sites were removed) allowed assessment of the contribution of each zinc finger on methylation activity at the target site. The sum of the methylation observed on each half site (43±5%) was less than methylation at the full target site (61±6%). The methylation observed with two distal half sites (<30%) was also less than that observed with the complete target site.