FIGURE 5.

Dimer interface disrupting mutants eliminate processive catalysis. Chase assays show DNMT3A homotetramers (WT) are processive and dimers (H873A and R882H) are non-processive, A, WT; B, H873A; and C, R882H. ●, only substrate (20 μm bp RASSF1A); ■, substrate and then 400 μm bp chase (pCpG^L) at 20 min; ▴, substrate and pCpG^L at the start of the reaction. Minimal methylation is detected after addition of chase DNA with the dimer mutant (H873A and R882H), unlike tetramer (WT), which shows less than 10% change in activity. D, homodimers that were formed by disrupting the dimer interface resulted in enzymes that bind DNA followed by methylation and then fast dissociation.