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Enhanced production of branched‐chain fatty acids by replacing β‐ketoacyl‐(acyl‐carrier‐protein) synthase III (FabH)
Author(s) -
Jiang Wen,
Jiang Yanfang,
Bentley Gayle J.,
Liu Di,
Xiao Yi,
Zhang Fuzhong
Publication year - 2015
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.25583
Subject(s) - atp synthase , acyl carrier protein , biochemistry , escherichia coli , chemistry , enzyme , acetyl coa , biosynthesis , acyl coa , stereochemistry , gene
Branched‐chain fatty acids (BCFAs) are important precursors for the production of advanced biofuels with improved cold‐flow properties. Previous efforts in engineering type II fatty acid synthase (FAS) for BCFA production suffered from low titers and/or the co‐production of a large amount of straight‐chain fatty acids (SCFAs), making it nearly impossible for further conversion of BCFAs to branched biofuels. Synthesis of both SCFAs and BCFAs requires FabH, the only β‐ketoacyl‐(acyl‐carrier‐protein) synthase in Escherichia coli that catalyzes the initial condensation reaction between malonyl‐ACP and a short‐chain acyl‐CoA. In this study, we demonstrated that replacement of the acetyl‐CoA‐specific E. coli FabH with a branched‐chain‐acyl‐CoA‐specific FabH directed the flux to the synthesis of BCFAs, resulting in a significant enhancement in BCFA titer compared to a strain containing both acetyl‐CoA‐ and branched‐chain‐acyl‐CoA‐specific FabHs. We further demonstrated that the composition of BCFAs can be tuned by engineering the upstream pathway to control the supply of different branched‐chain acyl‐CoAs, leading to the production either even‐chain‐iso‐, odd‐chain‐iso‐, or odd‐chain‐anteiso‐BCFAs separately. Overall, the top‐performing strain from this study produced BCFAs at 126 mg/L, comprising 52% of the total free fatty acids. Biotechnol. Bioeng. 2015;112: 1613–1622. © 2015 Wiley Periodicals, Inc.