Understanding nicotinamide dinucleotide cofactor and substrate specificity in class I flavoprotein disulfide oxidoreductases : crystallographic analysis of a glutathione amide reductase

Van Petegem, Filip; De Vos, Dirk; Savvides, Savvas; Vergauwen, Bjorn; Van Beeumen, Jozef

doi:10.1016/J.JMB.2007.09.072

Title

Understanding nicotinamide dinucleotide cofactor and substrate specificity in class I flavoprotein disulfide oxidoreductases : crystallographic analysis of a glutathione amide reductase

Author

Van Petegem, Filip

De Vos, Dirk

Savvides, Savvas

Vergauwen, Bjorn

Van Beeumen, Jozef

Abstract

Glutathione reductase (GR) plays a vital role in maintaining the antioxidant levels of the cytoplasm by catalyzing the reduction of glutathione disulfide to reduced glutathione, thereby using NADPH and flavin adenine dinucleotide as cofactors. Chromatiaceae have evolved an unusual homolog that prefers both a modified substrate (glutathione amide disulfide [GASSAG]) and a different cofactor (NADH). Herein, we present the crystal structure of the Chromatium gracile glutathione amide reductase (GAR) both alone and in complex with NAD+. An altered charge distribution in the GASSAG binding pocket explains the difference in substrate specificity. The NADH binding pocket of GAR differs from that of wild-type GR as well as that of a low active GR that was engineered to mimic NADH binding. Based on the GAR structure, we propose two attractive rationales for producing an efficient GR enzyme with NADH specificity.

Language

English

Source (journal)

Journal of molecular biology. - London

Publication

London : 2007

ISSN

0022-2836

DOI

10.1016/J.JMB.2007.09.072

Volume/pages

374 :4 (2007) , p. 883-889