FIG 2.

Phylogenetic tree of adenylation domains taken from fungal adenylate-forming reductases. Biochemical activities, domain structures, and the proposed class are indicated on the right. Four classes (I to IV) are represented by highly supported clades. Reductase domains of class I to III enzymes belong to the short-chain dehydrogenase/reductase (SDR) superfamily, and reductase domains of class IV enzymes belong to the ferredoxin-NADP⁺ reductase (FNR) superfamily. This suggests a domain swap event (arrow) where an ancestral SDR domain was replaced by an FNR domain. The tree was computed using the Bayesian inference implemented in MrBayes 3.2.2. PheA of Brevibacillus brevis was used as an outgroup to root the tree. Posterior probability values of >0.95 are shown next to the nodes. The scale bar indicates the expected changes per site.