Figure 6.

Sequence alignment of three archaeal DNA ligases and the human DNA ligase I fragment. Conserved residues are enclosed in blue boxes. η1, η2, η3, and η4 are 3₁₀-helices and TTs are tight β-turns. Residues in the A. fulgidus DNA ligase that interact with the bound phosphates are indicated by blue triangles. The alignment figure was made using the program ClustalX (Thompson et al., 1997 ▶) and ESPript (Gouet et al., 1999 ▶).