Z. Rui, Xin Li, Xuejun Zhu
Dec 8, 2014
Citations
9
Influential Citations
157
Citations
Quality indicators
Journal
Proceedings of the National Academy of Sciences
Abstract
Significance We have solved a long-standing mystery of the biosynthetic origin of 1-undecene, a ubiquitous hydrocarbon semivolatile metabolite of Pseudomonas. Our study revealed an unprecedented family of nonheme oxidases that specifically convert medium-chain fatty acids into the corresponding terminal olefins using an oxygen-activating, nonheme iron-dependent mechanism. Our findings unveil previously unidentified chemistry in the nonheme Fe(II) enzyme family, aid the functional study of this ubiquitous metabolite in Pseudomonas, expand the scarce enzyme inventory for the transformation of fatty acid precursors to hydrocarbons, and serve as the basis for engineering efforts to establish bioprocesses to produce medium-chain terminal olefins, useful as fuels and chemical building blocks, from renewable resources. Aliphatic medium-chain 1-alkenes (MCAEs, ∼10 carbons) are “drop-in” compatible next-generation fuels and precursors to commodity chemicals. Mass production of MCAEs from renewable resources holds promise for mitigating dependence on fossil hydrocarbons. An MCAE, such as 1-undecene, is naturally produced by Pseudomonas as a semivolatile 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, nonheme iron-dependent mechanism. Both biochemical and X-ray crystal structural analyses suggest an unusual mechanism of β-hydrogen abstraction during fatty acid substrate activation. Our discovery unveils previously unidentified chemistry in the nonheme 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.