Synthesis of the Ubiquitous Pseudomonas Hydrocarbon Semi-Volatile by an Unprecedented Non-Heme Iron Oxidase

Aliphatic medium-chain 1-alkenes (MCAEs, ~10 carbons) are “drop-in” compatible next-generation fuels and valuable precursors to commodity chemicals. Mass production of MCAEs from renewable resources holds promise for mitigating dependence on fossil hydrocarbons. MCAE, such as 1-undecene, is naturally produced by Pseudomonas as a semi-volatile metabolite through an unknown biosynthetic pathway. We describe here the discovery of a single gene conserved in Pseudomonas responsible for 1-undecene biosynthesis. The encoded enzyme is able to convert medium-chain fatty acids (C10-C14) into their corresponding terminal olefins using an oxygen-activating, non-heme iron dependent mechanism. Biochemical analysis suggests an unprecedented mechanism of β-hydrogen abstraction during fatty acid substrate activation. Our discovery unveils new chemistry in the non-heme Fe(II) enzyme family, provides an opportunity to explore the biology of 1-undecene in Pseudomonas, and paves the way for tailored bioconversion of renewable raw materials to MCAE-based biofuels and chemical commodities.