Figure 4.

Mn²⁺augments Polθ's repeat expansion capability.A, in vitro DNA synthesis assay using a synthesized oligonucleotide template containing 20 CTG repeats, which shows that Mn²⁺, but not Mg²⁺, triggers Polθ to conduct repeat expansions. B, in vitro DNA synthesis assay showing that Mn²⁺ stimulates Polθ, but not PolθΔi2 and Polδ, to carry out large repeat expansions when using an oligonucleotide containing 35 CTG repeats as a template. Polθ, DNA polymerase θ; PolθΔi2, insertion 2–depleted Polθ.