Figure 3
Dot1 enzymes share a distributive mode of action.
Experimental data of H3K79 methylation patterns generated by yDot1, TbDot1A, and TbDot1B in yeast and simulations using the models for distributive and processive enzymes as described in De Vos et al (2011)21. For each enzyme, the experimental H3K79 methylation pattern data that passed the quality test (presented in Fig. S3 and Supplemental Table SIII) were used to model the kinetic mechanism of the Dot1 enzymes. For yDot1, data from Frederiks et al22 were included. A subset of this dataset was confirmed by mass spectrometry analysis (see Supplemental Table SIII for numeric data). Simulations for hDot1L are shown in Supplemental Fig. S4. Each graph represents the H3K79 methylation patterns of yeast strains expressing a Dot1 enzyme at different concentrations. Each tick on the x-axis represents a single yeast strain. Simulations with the distributive model generated a better fit with the experimental data than the simulations with the processive model, as shown by the lower sum of squares values (SS).
