Substrate specificities of aromatic ring-hydroxylating oxygenases of an uncultured gammaproteobacterium from chronically-polluted subantarctic sediments

摘要: Abstract Aromatic ring-hydroxylating oxygenases (RHOs) are multicomponent enzymes that catalyze the vicinal hydroxylation of aromatic rings to produce cis-dihydrodiols, a key step in aerobic biodegradation compounds. In this work, we describe characterization three RHOs an uncultured gammaproteobacterium from chronically polluted Subantarctic intertidal sediments. Sequences encoding α and β subunits these RHOs, classified as class A type III, one set corresponding electron transfer partners, were identified 34 Kb fragment metagenomic fosmid library. Structural modeling docking analyses suggested active sites accommodated different substrates. The enzymes, including components, expressed Escherichia coli purified. enzyme with largest predicted catalytic pocket wider diameter channels presented remarkably relaxed substrate specificity, 2–4 ring PAHs (phenanthrene, pyrene, fluoranthene naphthalene). other two stricter their hydroxylated biphenyl naphthalene more efficiently. These results suggest evolution compatible RHO within single catabolic gene cluster microorganism. This work increases our understanding PAH-degrading capabilities bacteria cold coastal environments.