FIGURE 2.

Constructs and substrates used in this study. A, DNA encoding deletions of LigIIIβ were cloned into pET-28a with an N-terminal hexahistidine tag. The N- and C-terminal amino acids are listed for each construct that span the following domains: ZnF, DBD, NTase, and OBD. B, DNA substrates used in the fluorescence anisotropy binding experiments and end joining assays are shown. For DNA binding experiments, the template strand was 5′ fluorescein-labeled, as denoted by the asterisk. DNA end joining was assayed using substrates radiolabeled with ³²P on the 5′ terminus of the downstream strand. C, multiple sequence alignment of human DNA ligases showing only the conserved DBD, NTase, and OBD domains. The flanking N- and C-terminal sequences of the full-length proteins are not shown. Identical residues are highlighted, and conserved residues are boxed (18).