On the diversity of F420-dependent oxidoreductases: a sequence- and structure-based classification

Abstract

The F420 deazaflavin cofactor is an intriguing molecule as it structurally resembles the canonical flavin cofactor, although biochemically behaves as a nicotinamide cofactor. Since its discovery, numerous enzymes relying on it have been described. The known deazaflavoproteins are taxonomically restricted to Archaea and Bacteria. The biochemistry of the deazaflavoenzymes is diverse and they exhibit some degree of structural variability as well. In this study a thorough sequence and structural homology evolutionary analysis was performed in order to generate an overarching classification of all known F420-dependent oxidoreductases. Five different superfamilies are described: Superfamily I, TIM-barrel F420-dependent enzymes; Superfamily II, Rossmann fold F420-dependent enzymes; Superfamily III, {beta}-roll F420-dependent enzymes; Superfamily IV, SH3 barrel F420-dependent enzymes and Superfamily V, 3 layer {beta}{beta} sandwich F420-dependent enzymes. This classification aims to be the framework for the identification, the description and the understanding the biochemistry of novel deazaflavoenzymes.