Autoradiographs showing strand displacement of a labelled 24mer annealed to a 50mer to produce a template with a 3′ ssDNA region. Lanes are: (“boil”), substrate boiled for 5 mins in the absence of protein; (“no protein”), substrate alone; (“ice”), reaction incubated on ice; (“- ATP’), reaction without ATP; (“+EDTA”), reaction in the presence of 10 mM EDTA. Remaining lanes are reactions containing increasing concentrations of MthMCM protein indicated in nM (monomer). (A) WT, (B) RRAA, (C) R137A. (D) Quantification of DNA unwinding activity from experiments shown in (A) – (C). Unwinding was calculated as a percentage of 24mer displaced from the 50mer template. All points are an average of at least three experiments and error bars show the standard deviation from the mean. WT, closed circles, continuous line; R137A, open diamond, continuous line; RRAA, open circles, broken line.