Figure 1.

Heterologous DNA molecules increase Mre11 exonuclease activity. A total of 25 ng (0.3 pmol) of human recombinant Mre11 was incubated with 0.04 pmol of double-stranded DNA containing a 4-nt 5′ overhang, labeled at the 5′ end of the recessed strand. Immediately after combining Mre11 with the labeled substrate, various unlabeled DNA molecules were added, as indicated. The fold excess of competitor was calculated by using moles of DNA molecules. The reactions were stopped after 30 min and then run on a denaturing polyacrylamide gel.