F420-Dependent Glucose-6-Phosphate Dehydrogenase: A comprehensive review

Abstract F420-dependent glucose-6-phosphate dehydrogenase (FGD1) catalyzes the conversion of glucose-6-phosphate (G6P) to 6-phosphogluconolactone. During the course of this reaction, the oxidized cofactor F420 is converted to its reduced form (F420H2). FGD was initially identified and studied extensively within mycobacteria prior to the more recent discovery of FGDs from Rhodococcus jostii RHA1. Another group of FGDs that utilize a variety of sugar-6-phosphates from Nocardia and Cryptosporangium arvum is also known as the FSDs. Crystal structures of FGD from the pathogens Mycobacterium tuberculosis and Rhodococcus jostii RHA1 have provided significant insight into the structural and mechanistic properties of the enzymes and have been the basis for mutagenesis, kinetic and mechanistic studies in recent years. This review discusses the role of FGD within M. tuberculosis, followed by our current understanding of the FGD catalytic mechanism. This will also be discussed with reference to the relationship between FGD and the structurally unrelated NADP+-dependent glucose-6-phosphate enzymes.