Abstract:
:Branched-chain fatty acids (BCFAs) are key precursors of branched-chain fuels, which have cold-flow properties superior to straight chain fuels. BCFA production in Gram-negative bacterial hosts is inherently challenging because it competes directly with essential and efficient straight-chain fatty acid (SCFA) biosynthesis. Previously, Escherichia coli strains engineered for BCFA production also co-produced a large percentage of SCFA, complicating efficient isolation of BCFA. Here, we identified a key bottleneck in BCFA production: incomplete lipoylation of 2-oxoacid dehydrogenases. We engineered two protein lipoylation pathways that not only restored 2-oxoacid dehydrogenase lipoylation, but also increased BCFA production dramatically. E. coli expressing an optimized lipoylation pathway produced 276mg/L BCFA, comprising 85% of the total free fatty acids (FFAs). Furthermore, we fine-tuned BCFA branch positions, yielding strains specifically producing ante-iso or odd-chain iso BCFA as 77% of total FFA, separately. When coupled with an engineered branched-chain amino acid pathway to enrich the branched-chain α-ketoacid pool, BCFA can be produced from glucose at 181mg/L and 72% of total FFA. While E. coli can metabolize BCFAs, we demonstrated that they are not incorporated into the cell membrane, allowing our system to produce a high percentage of BCFA without affecting membrane fluidity. Overall, this work establishes a platform for high percentage BCFA production, providing the basis for efficient and specific production of a variety of branched-chain hydrocarbons in engineered bacterial hosts.
journal_name
Metab Engjournal_title
Metabolic engineeringauthors
Bentley GJ,Jiang W,Guamán LP,Xiao Y,Zhang Fdoi
10.1016/j.ymben.2016.07.003subject
Has Abstractpub_date
2016-11-01 00:00:00pages
148-158eissn
1096-7176issn
1096-7184pii
S1096-7176(16)30056-8journal_volume
38pub_type
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