Figure 2.

SDIMO α-subunit phylogeny and placement of IsoA. Maximum-likelihood phylogeny of soluble di-iron monooxygenase (SDIMO) α-subunits showing the placement of IsoA sequences from 11 confirmed isoprene degraders (Gram-positive and Gram-negative) relative to representative SDIMO groups. One to two representative sequences were retained per major SDIMO lineage (BmoX, PrmA, ThmA, TmoA) and six MmoX sequences, together with all IsoA sequences included in this study. IsoA forms a distinct, well-supported clade separated into Gram-positive (Rhodococcus, Gordonia, Mycobacterium, Nocardioides) and Gram-negative (Variovorax, Sphingopyxis, Ramlibacter) subclades. The analytical procedure encompassed 29 amino acid sequences with 617 positions in the final dataset. Scale bar represents amino acid substitutions per site. Accession numbers and full taxa are provided in Supplementary Table S5.