Phylogenetic tree derived from 53 molybdenum-binding oxidoreductases. The tree was constructed by using MEGA 4.1 neighbor-joining method with 500 bootstrap replicates. Genes annotated by IMG are color-coded; blue for TMAO reductase, purple for pyrogallol hydroxytransferase, red for DMSO reductase, green for nitrate reductase, and yellow for formate dehydrogenase. Genes that were newly assigned in this study for their potential protein function are indicated with arrows. Bootstrap values are shown for each node, and the scale indicates the number of amino acid substitutions per site.