FIGURE 4.

DNMT3A homodimers and homotetramers are active with different mechanisms. Disruption of the dimer interface reduces activity, but the dimers are still active with increased off-rates. The wild type tetramers are labeled gray and the dimer mutants are labeled blue. A and B, k_cat values of DNMT3A wild type and oligomeric mutants were determined on multisite substrates, poly-dIdC (A), and the human promoter RASSF1A (B.). Below are the wild type (gray) and dimer mutant R882H (blue) time course trace. C, eliminating tetramer formation in DNMT3A increased K_m^DNA (substrate poly-dIdC), above is the bar chart of K_m^DNA values, and below are the kinetic fits. D, DNMT3A homodimers have an increase in off-rate compared with homotetramers, above is the bar chart of k_off values determined on GCbox30, and below are the kinetic fits. All error bars were determined from at least three experiments given as S.E.; one-way analysis of variance was used to compare wild values to each mutant. *, p > 0.05; **, p > 0.01; ***, p > 0.001.