Predicted structure and function of divergent members of prokaryotic flavin adenine dinucleotide synthetase (FADS) proteins

Flavin adenine dinucleotide synthetases (FADSs) are well-known as a group of prokaryotic bifunctional enzymes that carry out the dual functions of riboflavin phosphorylation to produce flavin mononucleotide (FMN) and its subsequent adenylylation to generate FAD (hereafter FADS-type I). An extensive bioinformatics survey using the available genomes in public databases revealed that certain gram-positive pathogenic bacteria (i.e. Listeria monocytonegens, Listeria welshimeri, Lactobacillus plantarum, Bacillus cytotoxicus) and plant chloroplasts contain also variants of FADS sequences, named FADS-type II and plant-like FADS, respectively. Both variants of FADS proteins constitute distinct evolutionary classes characterized by shorter and non-conserved C-terminal domains. The putative structures and functions of the C-terminal domains of the FADS-type II from Listeria monocytonegens (LmFADS- typeII) and plant-like FADS from Glycine max. have been investigated. Previous results pointed out that the C-terminus domain of plant-like FADS proteins could contain a catalytic activity (i.e. hydrolase or phophatase), but different to that of their prokaryotic counterparts [1]. On the contrary, our recent investigations suggest that the C-terminus domain of LmFADS-type II might be related with the pathogenic activity of gram-positive bacteria, in particular with the defence of bacteria against the lytic action of host lysozimes [2]. This work is a contribution to our understanding of the evolutionary history of FADS enzymes. References [1] I. Yruela, S. Arilla-Luna, M. Medina, B. Contreras-Moreira. Evolutionary divergence of chloroplast FAD synthetase proteins (2010) BMC Evol. Biol. 10:311. [2] S. Leysen, L. Vanderkelen, S.D. Weeks, C.W. Michiels and S.V. Strelkov. Structural basis of bacterial defense against g-type lysozyme-based innate immunity (2013). Cell. Mol. Life Sci. 70:1113-1122.Peer Reviewe