From Structure-Function Analyses to Protein Engineering for Practical Applications of DNA Ligase

Figure 13

Roles of the C-terminal extension helix. (a) Alignment of the sequences of motif VI and the C-terminal extension. The sequences of the DNA ligases from a virus (ChV, Chlorella virus), bacteriophage (T7, bacteriophage T7), Archaea (Pfu, Pyrococcus furiosus; Tko, Thermococcus kodakaraensis), human (hu1, human DNA ligase I), and yeast (Sc1, Saccharomyces cerevisiae DNA ligase I) are aligned. The region for motif VI is shaded, and the extension helix region, determined by the crystal structures of PfuLig and hLigI, is colored red (residues after Q902 of hLigI were not included in the previously reported crystal structure and are colored gray). (b) Stereo diagram of the interface of the AdD and the OBD in PfuLig. Ball-and-stick models represent the amino acid residues involved in the interaction between the two domains: basic, acidic, and polar residues are colored blue, red, and purple, respectively. The C-terminal helix is colored red. The dotted lines indicate the polar or ionic interactions between AdD and OBD.

(a)

(b)