Fig. 2

Riboflavin-responsive mutants of FADS. A The alignment for the FADS catalytic domain was generated for known (or predicted) FADS sequences from human (Homo sapiens NP_079483.3), pig (Sus scrofa, XP_001929410.3), mouse (Mus musculus, NP_796015.2), frog (Xenopus laevis, XP_041427932.1), zebra fish (Danio rerio, NP_001003997.1), worm (Caenorhabditis elegans, NP_001022287.1), nematode (Trichinella pseudospiralis KRX89489.1), fruit fly (Drosophila melanogaster, NP_727648.1), yeast (Nakaseomyces glabratus, KTB21675.1), yeast (Saccharomyces cerevisiae EIW11165.1) and bacteria (Proteobacteria, MBQ30972.1) using ClustalX [113]. Amino acid numbers for the human sequence are indicated. Red boxes indicate the locations of the Ser495del and Arg530Cys human variants associated with adult-onset riboflavin-responsive disease. The bracket indicates the NGGKD motif that is important for FAD binding. Red arrows indicate Ile436, Met467 and Gly487 that are known to be important for FAD binding. Black boxes indicate Asp505, Trp508, Phe511 and Arg513 that are predicted to interact with the isoalloxazine rings. Ribbon diagrams (generated in VMD 1.9.1 [114] of the crystal structures of Saccharomyces cerevisiae Fad1p B [40] and Candida glabrata FMNAT C [41] in complex with FAD (white) are shown. Black boxed amino acids from panel A that are known to interact with isoalloxazine rings of FAD are highlighted in yellow (B, C). The conserved glycine (orange) in Fad1p and FMNAT that lies at the equivalent position to Ser495 in human FADS together with the conserved leucine (pink) at the equivalent position to Arg530 in human FADS flank the isoalloxazine ring-binding amino acids (yellow) in the primary structure