Figure 1. DNA Ligases.

A. Domains of the DNA ligase family proteins. DNA Ligases I, III, and IV constitute the mammalian DNA ligase family. All three members have a DNA binding domain (DBD), adenylation domain (AdD), and oligonucleotide binding domain (OBD). DNA Ligase III and IV both contain BRCA C-terminus (BRCT) domains at their C-terminus. Ligase III has a zinc finger (ZnF) domain and Ligase I has a nuclear localization signal (NLS) and proliferating cell nuclear antigen (PCNA) binding domain at the N-terminus. The amino acid position (Cole et al. 2008) of each domain is indicated above each diagram. B. LigIV truncation mutants. All mutants have an N-terminal myc tag and encompass the amino acids indicated in the name. The bars represent the conserved ATP-dependent ligase domains; ovals are BRCT domains. C. Degradation of LigIV truncation mutants by adenovirus. LigIV mutant plasmids were transfected into 293 cells which were subsequently either mock infected (−) or infected with H5dl1013 (+) for 20hrs. Cells were lysed, equal amounts of protein were loaded onto a polyacrylamide gel, and tagged LigIV was visualized by immunoblotting for the myc tag. The loading control is actin, and p53 is a control for adenovirus ubiquitin ligase function. U: Untransfected cells.