Figure 1.

Ligating two decamers using DNA ligase and templates containing tandem canonical bases at the site of ligation. (Left) Studies on only the n positions, showing both catalytic steps. (Right) Studies on the n – 1 positions, which also consist of experiments where the n positions are not base paired. The phosphorylated (represented by p) decamers are radiolabeled (represented by an asterisk) and are in italics. The names of the decamers to be ligated are represented by lower case lettering according to what nucleoside (from 5′ to 3′) is paired with the universal template positions (in the gray box). The template names are in upper case and represent the central universal template positions (underlined). Note that the adenylation step consists of a 5′→5′ phosphate bond between the phosphorylated decamer and an AMP cofactor. Unless otherwise noted, all oligonucleotides are written in the 5′→3′ direction. Be aware that, although we have no evidence to the contrary, hybridization of each oligonucleotide to the template might not be precisely as drawn here.