Structure, Function, and Insights into the Biosynthesis of a Head-to-Head Hydrocarbon in Shewanella oneidensis Strain MR-1

Abstract

A polyolefinic hydrocarbon was found in nonpolar extracts of Shewanella oneidensis MR-1 and identified as 3,6,9,12,15,19,22,25,28-hentriacontanonaene (compound I) by mass spectrometry, chemical modification, and nuclear magnetic resonance spectroscopy. Compound I was shown to be the product of a head-to-head fatty acid condensation biosynthetic pathway dependent on genes denoted as ole (for olefin biosynthesis). Four ole genes were present in S. oneidensis MR-1. Deletion of the entire oleABCD gene cluster led to the complete absence of nonpolar extractable products. Deletion of the oleC gene alone generated a strain that lacked compound I but produced a structurally analogous ketone. Complementation of the oleC gene eliminated formation of the ketone and restored the biosynthesis of compound I. A recombinant S. oneidensis strain containing oleA from Stenotrophomonas maltophilia strain R551-3 produced at least 17 related long-chain compounds in addition to compound I, 13 of which were identified as ketones. A potential role for OleA in head-to-head condensation was proposed. It was further proposed that long-chain polyunsaturated compounds aid in adapting cells to a rapid drop in temperature, based on three observations. In S. oneidensis wild-type cells, the cellular concentration of polyunsaturated compounds increased significantly with decreasing growth temperature. Second, the oleABCD deletion strain showed a significantly longer lag phase than the wild-type strain when shifted to a lower temperature. Lastly, compound I has been identified in a significant number of bacteria isolated from cold environments.

Terminal Olefin (1-Alkene) Biosynthesis by a Novel P450 Fatty Acid Decarboxylase from Jeotgalicoccus Species

“…The first hydrocarbon biosynthesis genes were discovered in a genetic screen for Stenotrophomonas maltophilia mutants unable to synthesize long-chain olefins (20). Based on this work, the homologous genes from Micrococcus luteus (7) and Shewanella oneidensis (49) were characterized. The key enzyme of the long-chain olefin biosynthesis, OleA, is a homolog of the condensing enzyme FabH (3-oxo-acyl-ACP ketosynthase III), which likely acts through a thiolase reaction mechanism.…”

Active Multienzyme Assemblies for Long-Chain Olefinic Hydrocarbon Biosynthesis

“…The purification of individually expressed OleA, OleC, and OleD proteins derived from different bacteria had been reported previously (5,(7)(8)(9)(10)(11), while the purification of an OleB protein is reported here for the first time, to our knowledge. In this study, all four X. campestris Ole proteins were purified in a recombinant form from separate E. coli expression host cell lines.…”

“…The cellular function(s) of the ole gene cluster has been studied only in Shewanella oneidensis MR-1. The presence of the oleABCD genes was found to promote more rapid cell growth during a shift to colder temperatures, consistent with those genes being commonly found in cold-temperature bacteria from polar and marine environments (4)(5)(6). However, bacteria containing ole gene clusters inhabit a diversity of ecological niches, suggesting there may be a range of functions for long-chain olefinic hydrocarbons.…”

Yarrowia lipolytica as an Oleaginous Cell Factory Platform for Production of Fatty Acid-Based Biofuel and Bioproducts

“…In this pathway, two FAs become connected through their carboxyl group releasing the carboxyl group and generating double bonds at the linkage point. Heterologous expression of these genes allows for long-chain olefinic hydrocarbon or monoketone production to the host cell (Sukovich et al, 2010). FA-overproducing E. coli has been used as platform for the biosynthesis of large chain alkenes.…”