Fig. 2: ORC molecules exhibit diffusive motion that is halted at origins.

a, b (i) Sample time traces and (ii) scan images that illustrate the observed motion of JF549-ORC initially localized a within 0.2 µm of the HtH origin or b in any other location. Traces shown represent 3% (randomly selected) of traces from all four biochemical conditions described in Fig. 1. c (i) Sample time traces and (ii) scan images that illustrate the four main types of motion observed for JF549-ORC: (1) static; (2) diffusive; (3) static and then diffusive; (4) diffusive and then static. d Histogram of the diffusion constants of ORC incubated in the presence of ATPγS. Only foci containing 1 or 2 ORC were considered. The two populations of diffusion constants fit to log-normal distributions (solid black lines), taking into account the error bars derived from bootstrapping the data set 100 times. This yields populations with mean ± SEM of 0.06 ± 0.04 kbp² s⁻¹ (59% of the distribution) and 0.97 ± 0.09 kbp² s⁻¹ (p < 0.0001 by one-way ANOVA). e As in d, except that the DNA contains the mHtH origin described in Supplementary Fig. 7. Here, fitting yields populations with mean ± SEM 0.05 ± 0.03 kbp² s⁻¹ (26%) and 0.88 ± 0.09 kbp² s⁻¹ (p < 0.0001 by one-way ANOVA). f Quantification of the percent of ORC molecules initially bound in a given location, which go on to display slow diffusion: (i) ORC molecules initially bound within 0.2 µm of the HtH origin; (ii) ORC molecules initially bound within 0.2 µm of origin-like sequences; (iii) ORC molecules initially bound elsewhere. Error bars represent the error of sample proportion, sqrt(p(1−p)/n), where p is the proportion of a sample in a given population, and n is the sample size.