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. 2005 Nov 17;24(23):4188–4197. doi: 10.1038/sj.emboj.7600881

Figure 2.

Figure 2

Dependence of the translocation activity on the motor subunit concentration. (A) Two time traces recorded in the magnetic tweezers at HsdR concentrations of 10 and 300 nM. The MTase concentration is 20 nM and the applied stretching force 0.8 pN. (B) The cumulative event number versus time of the occurrence of the event for various HsdR concentrations. The cumulative event number is obtained from time traces as in panel A by numbering every single translocation event consecutively. (C) Triple helix displacement profiles derived from stopped-flow experiments at low HsdR concentrations. Reactions were initiated by mixing preincubated triplex DNA, MTase and HsdR with an equal volume of reaction buffer with ATP (final concentration 4 mM). The triplex is 2047 bp away from the EcoR124I binding site. The final solution contains 30 nM MTase and 5 nM DNA, of which 2.5 nM carries one triplex. Therefore, only 25% of the translocation events can lead to triplex displacement, because there are 10 nM HsdR binding sites available (two per DNA-bound MTase).