Model of PriSL-mediated DSB repair. When a DNA DSB occurs, PriSL binds directly or is recruited to the site of the DSB. PriS in the DNA-bound PriSL heterodimer is positioned proximal to the 3′-end of a DNA strand on one side of the DSB. Facilitated by PriL, the 3′-end, with or without the addition of nucleotides by terminal transfer reaction, searches for and anneals to a sequence with microhomology, at the 3′-end of a DNA strand similarly bound by PriSL, on the other side of the break point. Once the broken ends are bridged, chain extension by PriSL occurs, followed by polishing through the activities of nucleases, DNA Pol and Lig.