In silico assessment of the metabolic capabilities of an engineered functional reversal of the β-oxidation cycle for the synthesis of longer-chain (C≥4) products

Escherichia coli Enoyl-Acyl Carrier Protein Reductase (FabI) Supports Efficient Operation of a Functional Reversal of the β-Oxidation Cycle

“…Unlike the use of NADH, which can be regenerated through numerous metabolic reactions, the regeneration of a reduced ferredoxin requires the use of a pyruvate ferredoxin oxidoreductase (54) during the conversion of pyruvate to acetyl-CoA. This can have a pronounced impact on overall redox balance, as the requirement for the generation of an additional reducing equivalent through this step can lead to an accumulation of reducing equivalents during the synthesis of certain products (55). Thus, uncoupling the enoyl-CoA reduction from both thermodynamic and stoichiometric constraints through the use of an NADH-dependent enzyme, such as FabI, can greatly increase the ability of a functional reversal of the ␤-oxidation cycle to produce all potential products at higher theoretical yields.…”

“…A similar approach with additional types of termination pathways, such as acyl-CoA reductases for alcohol production, can also be utilized to diversify product synthesis. In addition to the production of carboxylic acids and n-alcohols through the tailoring of termination pathways, the promiscuous nature of ENRs can potentially be further exploited within the context of a ␤-oxidation reversal through the use of various priming molecules, which can lead to the synthesis of a diverse set of products with a wide range of functional groups (55).…”

Integrated engineering of β-oxidation reversal and ω-oxidation pathways for the synthesis of medium chain ω-functionalized carboxylic acids

“…While several pathways have been investigated for this purpose, the recently engineered reversal of the β-oxidation cycle provides an attractive platform that can support the synthesis of short-, medium-, and long-chain products at high yields (Clomburg et al, 2012;Dellomonaco et al, 2011;Gulevich et al, 2012;Lian and Zhao, 2014;Zhuang et al, 2014). In addition to key characteristics that could enable product synthesis at maximum carbon and energy efficiency, such as operation with CoA intermediates as well as the use of acetyl-CoA as the extender unit for acyl-CoA elongation, the β-oxidation reversal can be potentially used to generate a diverse set of products (Cintolesi et al, 2014). Among these, the production of compounds with functionality at the ω carbon is of great interest as a number of industrially important products, such as dicarboxylic acids, ω-hydroxyacids, and α,ω-diols, are contained in this broad class.…”

Engineering an iterative polyketide pathway in Escherichia coli results in single-form alkene and alkane overproduction

“…As summarized in Fig. S1, thus far there have been five reported pathways for engineering alkane and alkene production derived from the fatty acid system (Beller et al, 2010;Choi and Lee, 2013;Howard et al, 2013;Rude et al, 2011;Schirmer et al, 2010;Sukovich et al, 2010), as well as a reversed β-oxidation pathway demonstrated by an in silico modeling study (Cintolesi et al, 2014). Short-chain alkanes can be produced at levels exceeding 500 mg/L through fatty acyl-acyl carrier protein (ACP) to fatty acid to fatty acyl-CoA pathway (Choi and Lee, 2013).…”