FIG 6.

(a) Superposition of the five RHOs (NidA, NidA3, BPDO from Rhodococcus sp. strain RHA-1, NDO from P. putida NCIB 9816-4, and PhnI from Sphingomonas sp. strain CHY-1) substrate-binding pockets. The mononuclear Fe²⁺ and spatially conserved aromatic amino acids are represented as a red ball and a stick model, respectively. (b to d) Schematic diagrams show the interactions between the substrates and amino acid residues in the active sites for the following substrates: phenanthrene and NDO from P. putida NCIB 9816-4 (b), pyrene and NidA (c), and fluoranthene and NidA3 (d). The van der Waals interactions are indicated by pink shading. Asterisks indicate spatially conserved aromatic amino acids. Refer to Table SA3 in the supplemental material for the list of amino acid residues.