Synthesis of customized petroleum-replica fuel molecules by targeted modification of free fatty acid pools in
            <i>Escherichia coli</i>

Howard, Thomas P.; Middelhaufe, Sabine; Moore, Karen; Edner, Christoph; Kolak, Dagmara; Taylor, G.N.; Parker, David; Lee, Robert J.; Smirnoff, Nicholas; Aves, Stephen J.; Love, John

doi:10.1073/pnas.1215966110

Cited by 163 publications

(147 citation statements)

References 45 publications

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“…A similar challenge of limiting unwanted flux from aldehyde intermediates to alcohol byproducts has been encountered in the context of alkane production. The final step to alkane biosynthesis features the conversion of a C n aldehyde to a C nϪ1 alkane catalyzed by an aldehyde decarbonylase or aldehyde deformylating oxygenase (26,(58)(59)(60)(61)(62). Although the problem of alcohol byproduct formation has been described extensively, very few studies of alkane biosynthesis have used strains engineered with deletions of aldehyde reductases.…”

Section: Enhancing Bioconversion Of Aldehydes To Other Chemical Classesmentioning

confidence: 99%

Microbial Engineering for Aldehyde Synthesis

Kunjapur

Prather

2015

Appl Environ Microbiol

145

129

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Aldehydes are a class of chemicals with many industrial uses. Several aldehydes are responsible for flavors and fragrances present in plants, but aldehydes are not known to accumulate in most natural microorganisms. In many cases, microbial production of aldehydes presents an attractive alternative to extraction from plants or chemical synthesis. During the past 2 decades, a variety of aldehyde biosynthetic enzymes have undergone detailed characterization. Although metabolic pathways that result in alcohol synthesis via aldehyde intermediates were long known, only recent investigations in model microbes such as Escherichia coli have succeeded in minimizing the rapid endogenous conversion of aldehydes into their corresponding alcohols. Such efforts have provided a foundation for microbial aldehyde synthesis and broader utilization of aldehydes as intermediates for other synthetically challenging biochemical classes. However, aldehyde toxicity imposes a practical limit on achievable aldehyde titers and remains an issue of academic and commercial interest. In this minireview, we summarize published efforts of microbial engineering for aldehyde synthesis, with an emphasis on de novo synthesis, engineered aldehyde accumulation in E. coli, and the challenge of aldehyde toxicity.

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Section: Enhancing Bioconversion Of Aldehydes To Other Chemical Classesmentioning

confidence: 99%

Microbial Engineering for Aldehyde Synthesis

Kunjapur

Prather

2015

Appl Environ Microbiol

145

129

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“…However, the function of hydrocarbons in cyanobacteria has not been determined. Characterization of cyanobacterial hydrocarbon biosynthesis pathways has provided the basis for investigating synthetic microbial biofuel systems, which may be a renewable substitute for fossil fuels (Schirmer et al, 2010;Choi and Lee, 2013;Howard et al, 2013). However, secretion of long-chain hydrocarbons from the cell into the medium, which is likely essential for commercially viable production, has not been observed in the absence of a membrane solubilization agent (Schirmer et al, 2010;Tan et al, 2011).…”

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confidence: 99%

Hydrocarbons Are Essential for Optimal Cell Size, Division, and Growth of Cyanobacteria

et al. 2016

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Cyanobacteria are intricately organized, incorporating an array of internal thylakoid membranes, the site of photosynthesis, into cells no larger than other bacteria. They also synthesize C15-C19 alkanes and alkenes, which results in substantial production of hydrocarbons in the environment. All sequenced cyanobacteria encode hydrocarbon biosynthesis pathways, suggesting an important, undefined physiological role for these compounds. Here, we demonstrate that hydrocarbon-deficient mutants of Synechococcus sp. PCC 7002 and Synechocystis sp. PCC 6803 exhibit significant phenotypic differences from wild type, including enlarged cell size, reduced growth, and increased division defects. Photosynthetic rates were similar between strains, although a minor reduction in energy transfer between the soluble light harvesting phycobilisome complex and membrane-bound photosystems was observed. Hydrocarbons were shown to accumulate in thylakoid and cytoplasmic membranes. Modeling of membranes suggests these compounds aggregate in the center of the lipid bilayer, potentially promoting membrane flexibility and facilitating curvature. In vivo measurements confirmed that Synechococcus sp. PCC 7002 mutants lacking hydrocarbons exhibit reduced thylakoid membrane curvature compared to wild type. We propose that hydrocarbons may have a role in inducing the flexibility in membranes required for optimal cell division, size, and growth, and efficient association of soluble and membrane bound proteins. The recent identification of C15-C17 alkanes and alkenes in microalgal species suggests hydrocarbons may serve a similar function in a broad range of photosynthetic organisms.

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“…Recent efforts in microbial biofuel production hinge upon constructing efficient metabolic pathways to produce a variety of fatty acids (FA)-based fuels (17)(18)(19)(20)(21)(22)(23). To date, most of the work has taken a static perspective to coordinate the expression of enzymes and optimize production titer and yield, including modification of plasmid copy number (24), promoter strength (25,26), and combinations of these strategies (21,27).…”

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confidence: 99%

Improving fatty acids production by engineering dynamic pathway regulation and metabolic control

Zhang

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

441

358

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Global energy demand and environmental concerns have stimulated increasing efforts to produce carbon-neutral fuels directly from renewable resources. Microbially derived aliphatic hydrocarbons, the petroleum-replica fuels, have emerged as promising alternatives to meet this goal. However, engineering metabolic pathways with high productivity and yield requires dynamic redistribution of cellular resources and optimal control of pathway expression. Here we report a genetically encoded metabolic switch that enables dynamic regulation of fatty acids (FA) biosynthesis in Escherichia coli. The engineered strains were able to dynamically compensate the critical enzymes involved in the supply and consumption of malonyl-CoA and efficiently redirect carbon flux toward FA biosynthesis. Implementation of this metabolic control resulted in an oscillatory malonyl-CoA pattern and a balanced metabolism between cell growth and product formation, yielding 15.7-and 2.1-fold improvement in FA titer compared with the wild-type strain and the strain carrying the uncontrolled metabolic pathway. This study provides a new paradigm in metabolic engineering to control and optimize metabolic pathways facilitating the high-yield production of other malonyl-CoA-derived compounds.biofuels | dynamic metabolic control | transcriptional regulation A grand challenge in synthetic biology is to move the design of biomolecular circuits from purely genetic constructs toward systems that integrate different levels of cellular complexity, including regulatory networks and metabolic pathways (1). Despite the fact that a large volume of regulatory architectures and motifs has been discovered (2, 3), little has been accomplished in pathway engineering to improve cellular productivity and yield by exploiting dynamic pathway regulation and metabolic control (4). One essential part in implementing synthetic metabolic control in pathway engineering is to engineer novel metabolite sensors with desired input-output relationships. For example, have designed and applied a regulatory circuit that can sense the glycolytic pathway hallmark metabolite acetylphosphate to control the lycopene biosynthetic pathway (5) and generate oscillatory gene expression (6) as well as achieve artificial cell-cell communication (7). Dahl et al. (8) have used stressresponse promoters to improve farnesyl pyrophosphate production, and Tsao et al. (9) have rewired the Escherichia coli native quorumsensing regulon for autonomous induction of recombinant proteins.Traditional metabolic engineering is largely focused on the overexpression of rate-limiting steps (10

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Synthesis of customized petroleum-replica fuel molecules by targeted modification of free fatty acid pools in Escherichia coli

Cited by 163 publications

References 45 publications

Microbial Engineering for Aldehyde Synthesis

Microbial Engineering for Aldehyde Synthesis

Hydrocarbons Are Essential for Optimal Cell Size, Division, and Growth of Cyanobacteria

Improving fatty acids production by engineering dynamic pathway regulation and metabolic control

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