Supplementary Figure 9: Nick translation.
From: epiGBS: reference-free reduced representation bisulfite sequencing
(a) Due to the use of non-phosphorylated adapters, epiGBS libraries contain nicks between the 3’ fragment overhang and the 5’ non-phosphorylated adapter nucleotide (on the bottom strand in this Figure). To prevent the partial loss of adapter sequence during bisulfite treatment the nick was repaired by DNA polymerase I. DNA polymerase I is able to repair single stranded nicks in dsDNA in two steps. (b) first it removes the nucleotide (in this case C) at the 5’ side of the nick by 5’-3’ exonuclease activity after which (c) the 3’ hydroxyl terminus is elongated with a single dNTP (in this case 5mC) using the nucleotide from the opposite strand (here G) as template. DNA polymerase I moves one nucleotide downstream towards the 3’ end of the bottom adapter strand. Steps (b) and (c) are repeated until the 3’ end of the adapter is reached, leaving no nicks in the adapter sequence.
