ATP drives direct photosynthetic production of 1-butanol in Cyanobacteria

Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 04/2012; 109(16):6018-23. DOI: 10.1073/pnas.1200074109
Source: PubMed


While conservation of ATP is often a desirable trait for microbial production of chemicals, we demonstrate that additional consumption of ATP may be beneficial to drive product formation in a nonnatural pathway. Although production of 1-butanol by the fermentative coenzyme A (CoA)-dependent pathway using the reversal of β-oxidation exists in nature and has been demonstrated in various organisms, the first step of the pathway, condensation of two molecules of acetyl-CoA to acetoacetyl-CoA, is thermodynamically unfavorable. Here, we show that artificially engineered ATP consumption through a pathway modification can drive this reaction forward and enables for the first time the direct photosynthetic production of 1-butanol from cyanobacteria Synechococcus elongatus PCC 7942. We further demonstrated that substitution of bifunctional aldehyde/alcohol dehydrogenase (AdhE2) with separate butyraldehyde dehydrogenase (Bldh) and NADPH-dependent alcohol dehydrogenase (YqhD) increased 1-butanol production by 4-fold. These results demonstrated the importance of ATP and cofactor driving forces as a design principle to alter metabolic flux.

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    • "The ability of cyanobacteria to grow in simple media and use sunlight to capture carbon dioxide has also made them an increasingly attractive target for industrial bioprocess applications. These applications include for the production of biofuels, such as alkane [1] [2], butanol [3] [4], isobutyraldehyde [5], and fatty acids [6], or for the production of other chemicals, such as polyhydroxybutyrate [7] and isoprene [8]. Although a number of researchers have successfully engineered cyanobacteria for various applications, there remains a need for tools to effectively display recombinant proteins on the surface of cyanobacterial cells. "
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    ABSTRACT: The autotransporter protein antigen 43 from Escherichia coli was recombinantly expressed in the cyanobacterium Synechocystis sp. PCC6803, under the regulation of the green light-inducible promoter PcpcG2. Antigen 43 expression was induced in response to green light, resulting in the constant accumulation of the protein for at least four days. The complete post-translational processing of the antigen 43 protein was confirmed by Western blot analysis. The resulting antigen 43 α chain was essentially all displayed on the cell surface, as confirmed by proteinase K treatment. Although microbial cell-surface-display technology has a wide range of biotechnological applications, this is the first report of an efficient method for the display of recombinant proteins in cyanobacteria.
    Algal Research 11/2015; 12:337-340. DOI:10.1016/j.algal.2015.09.013 · 5.01 Impact Factor
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    • "Cyanobacteria Compound Production References Synechococcus elongatus PCC 7942 Ethanol 230 mg/L [11] Synechocystis sp. PCC 6803 Ethanol 5500 mg/L [12] Synechococcus elongatus PCC 7942 Isobutanol 450 mg/L [13] Synechococcus elongatus PCC 7942 Isobutyraldehyde 1100 mg/L [13] Synechococcus elongatus PCC 7942 1-Butanol 29.9 mg/L [14] Anabaena sp. PCC 7120 Hydrogen 2.6 í µí¼‡mol mg −1 chl a h −1 [15] Anabaena cylindrica IAM M-1 Hydrogen 2.1 í µí¼‡mol mg −1 chl a h −1 [15] "
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    ABSTRACT: Cyanobacteria are widely distributed Gram-negative bacteria with a long evolutionary history and the only prokaryotes that perform plant-like oxygenic photosynthesis. Cyanobacteria possess several advantages as hosts for biotechnological applications, including simple growth requirements, ease of genetic manipulation, and attractive platforms for carbon neutral production process. The use of photosynthetic cyanobacteria to directly convert carbon dioxide to biofuels is an emerging area of interest. Equipped with the ability to degrade environmental pollutants and remove heavy metals, cyanobacteria are promising tools for bioremediation and wastewater treatment. Cyanobacteria are characterized by the ability to produce a spectrum of bioactive compounds with antibacterial, antifungal, antiviral, and antialgal properties that are of pharmaceutical and agricultural significance. Several strains of cyanobacteria are also sources of high-value chemicals, for example, pigments, vitamins, and enzymes. Recent advances in biotechnological approaches have facilitated researches directed towards maximizing the production of desired products in cyanobacteria and realizing the potential of these bacteria for various industrial applications. In this review, the potential of cyanobacteria as sources of energy, bioactive compounds, high-value chemicals, and tools for aquatic bioremediation and recent progress in engineering cyanobacteria for these bioindustrial applications are discussed.
    BioMed Research International 07/2015; 2015(2). DOI:10.1155/2015/754934 · 2.71 Impact Factor
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    • "An exogenous MVA pathway was introduced into the cyanobacterium Synechocystis PCC 6803, coupled with the heterologous expression of an isoprene synthase, in which the isoprene yield only reached 250 lg/g gcw (Bentley et al., 2014). A possible reason for the low terpene yield through the MVA pathway is that acetyl-CoA pool in photosynthetic organisms is low under photosynthetic conditions (Lan and Liao, 2012). Compared to cyanobacteria, the plant and algae MEP pathway enzymes are compartmentalized in chloroplasts. "

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