Crystal structure of UDP-galactose 4-epimerase from the hyperthermophilic archaeon Pyrobaculum calidifontis

► The crystal structure of the hyperthermophilic UDP-galactose 4-epimerase (GalE) was determined. ► The hydrophobic inter-subunit interaction is responsible for the enzyme stability. ► The loop responsible for the tight binding of NAD to the enzyme was identified. ► This is the first report on the structure of a GalE in a hyperthermophile.