The cytochrome P450 decarboxylase from Staphylococcus aureus can produce a diene from a C18 monounsaturated fatty acid: A spectroscopic, structural and kinetic characterisation

Volume 275, February 2026, 113117

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OleTSa is co-purified with a monounsaturated fatty acid.

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The co-purified fatty acid is determined to be elaidic acid.

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OleTSa has a 3-fold higher affinity for an unsaturated vs a saturated fatty acid.

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OleTSa reacts with H2O2 to decarboxylate elaidic acid and form heptadeca-1,8-diene.

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Site-directed variants in the fatty acid binding cavity do not alter chemoselectivity.

Abstract

Certain members of the bacterial cytochrome P450 152 family (CYP152) are peroxygenases that catalyse the decarboxylation of fatty acids into terminal olefins making them attractive biocatalysts for biofuel production. To date, the characterisation of decarboxylating CYP152s has mainly focused on their reaction with saturated fatty acid substrates. CYP152s are often co-purified with a bound substrate, which is generally removed before further experiments are conducted. In the present work we identified that heterologous over-expressed CYP152 from Staphylococcus aureus (OleTSa) is co-purified with the trans-monounsaturated C18:1 fatty acid, elaidic acid. We report the spectral, thermodynamic and kinetic characteristics of OleTSa bound to both elaidic acid and its saturated counterpart, stearic acid. Despite differing spectral profiles, metabolic and kinetic studies reveal that OleTSa is capable of decarboxylating elaidic acid, converting it to heptadeca-1,8-diene following addition of hydrogen peroxide, at the same rate and chemoselectivity as the conversion of stearic acid to 1-heptadecane. The X-ray crystal structure of the as purified OleTSa in complex with elaidic acid is also presented, allowing for several key residues to be identified for site-directed mutagenesis studies. The influence of the site-directed variants on C18:0 and C18:1 product formation, binding thermodynamics and kinetics have been investigated, showing that while spectral differences occur as a likely result of perturbing the binding pocket, this does not alter the chemoselectivity of the enzyme. Our work provides important insights into the mechanism of decarboxylation of an unsaturated fatty acid substrate by OleTSa potentially expanding the sustainable substrate space available for CYP152s.

Graphical abstractThe CYP152 peroxygenase, OleTSa, co-purifies with a C18 monounsaturated fatty acid, identified as elaidic acid. X-ray crystallography confirms the presence of the trans-C18 isomer. Metabolic profiling and kinetic studies reveal OleTSa can decarboxylate elaidic acid to form heptadeca-1,8-diene following addition of the co-substrate H2O2. Unlabelled Image