The enzyme aldos-2-ulose dehydratase/isomerase (AUDH) participates in carbohydrate secondary metabolism, catalyzing the conversion of glucosone and 1,5-d-anhydrofructose to the secondary metabolites cortalcerone and microthecin, respectively. Crystal structure analysis revealed that the enzyme subunit is built up of three domains, an N-terminal seven-bladed propeller, a bicupin and a C-terminal lectin domain. This entry describes the second Cupin domain (residues 574-739) composed of two antiparallel sheets that build up the jellyroll sandwich fold formed from four and five beta-strands. This cupin domain in AUDH is found to contain a zinc binding site where the metal site is located at the bottom of the cleft formed by the beta-sandwich, as observed in many cupins [1].

1: Crystal structure of bifunctional aldos-2-ulose dehydratase/isomerase from Phanerochaete chrysosporium with the reaction intermediate ascopyrone M. Claesson M, Lindqvist Y, Madrid S, Sandalova T, Fiskesund R, Yu S, Schneider G; J Mol Biol. 2012;417:279-293. PMID:22330145

2: Crystal structure of a peptidoglycan synthesis regulatory factor (PBP3) from Streptococcus pneumoniae. Morlot C, Pernot L, Le Gouellec A, Di Guilmi AM, Vernet T, Dideberg O, Dessen A; J Biol Chem. 2005;280:15984-15991. PMID:15596446