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Publication Abstract from PubMed

Previously, some bacteria were shown to harbour enzymes capable of catalysing the oxidative cleavage of the double bond of t-anethole and related compounds. The cofactor dependence of these enzymes remained enigmatic due to a lack of biochemical information. We report on catalytic and structural details of a representative of this group of oxidative enzymes: t-anethole oxygenase from Stenotrophomonas maltophilia (TAO(Sm)). The bacterial enzyme could be recombinantly expressed and purified, enabling a detailed biochemical study that has settled the dispute on its cofactor dependence. We have established that TAO(Sm) contains a tightly bound b-type heme and merely depends on dioxygen for catalysis. It was found to accept t-anethole, isoeugenol and O-methyl isoeugenol as substrates, all being converted into the corresponding aromatic aldehydes without the need of any cofactor regeneration. The elucidated crystal structure of TAO(Sm) has revealed that it contains a unique active site architecture that is conserved for this distinct class of heme-containing bacterial oxygenases. Similar to other hemoproteins, TAO(Sm) has a histidine (His121) as proximal ligand. Yet, unique for TAOs, an arginine (Arg89) is located at the distal axial position. Site directed mutagenesis confirmed crucial roles for these heme-liganding residues and other residues that form the substrate binding pocket. In conclusion, the results reported here reveal a new class of bacterial heme-containing oxygenases that can be used for the cleavage of alkene double bonds, analogous to ozonolysis in organic chemistry.

Discovery of a new class of bacterial heme-containing CC cleaving oxygenases.,Purwani NN, Rozeboom HJ, Willers VP, Wijma HJ, Fraaije MW N Biotechnol. 2024 Jul 23;83:82-90. doi: 10.1016/j.nbt.2024.07.002. PMID:39053683^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.