1A0I:
reference: Crystal structure of an ATP-dependent DNA ligase from bacteriophage T7., Subramanya HS, Doherty AJ, Ashford SR, Wigley DB, Cell 1996 May 17;85(4):607-15. PMID: 8653795

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).