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The plasticity of cyanobacterial metabolism supports direct CO2 conversion to ethylene

An Erratum to this article was published on 18 May 2015

Abstract

The cyanobacterial tricarboxylic acid (TCA) cycle functions in both in biosynthesis and energy generation. However, it has until recently been generally considered to be incomplete1,2 with limited flux3,4, and few attempts have been made to draw carbon from the cycle for biotechnological purposes. We demonstrated that ethylene can be sustainably and efficiently produced from the TCA cycle of the recombinant cyanobacterium Synechocystis 6803 expressing the Pseudomonas ethylene-forming enzyme (Efe)5. A new strain with a modified ribosome binding site upstream of the efe gene diverts 10% of fixed carbon to ethylene and shows increased photosynthetic activities. The highest specific ethylene production rate reached 718 ± 19 μl l–1 h–1 per A730 nm. Experimental and computational analyses based on kinetic 13C-isotope tracer and liquid chromatography coupled with mass spectrometry (LC–MS) demonstrated that the TCA metabolism is activated by the ethylene forming reaction, resulting in a predominantly cyclic architecture. The outcome significantly enhanced flux through the remodelled TCA cycle (37% of total fixed carbon) compared with a complete, but bifurcated and low-flux (13% of total fixed carbon) TCA cycle in the wild type. Global carbon flux is redirected towards the engineered ethylene pathway. The remarkable metabolic network plasticity of this cyanobacterium is manifested by the enhancement of photosynthetic activity and redistribution of carbon flux, enabling efficient ethylene production from the TCA cycle.

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Figure 1: Ethylene production in a transgenic cyanobacterium.
Figure 2: Efe expression and ethylene productivity.
Figure 3: The TCA cycle fluxes analysed by glutamate labelling.
Figure 4: Comparison of metabolism of Synechocystis WT and the ethylene-producing strain JU547.

References

  1. 1

    Pearce, J., Leach, C. K. & Carr, N. G. The incomplete tricarboxylic acid cycle in the blue-green alga Anabaena variabilis. J. Gen. Microbiol. 55, 371–378 (1969).

    CAS  Article  Google Scholar 

  2. 2

    Smith, A. J., London, J. & Stanier, R. Y. Biochemical basis of obligate autotrophy in blue-green algae and thiobacilli. J. Bacteriol. 94, 972–983 (1967).

    CAS  PubMed  PubMed Central  Google Scholar 

  3. 3

    Young, J. D., Shastri, A. A., Stephanopoulos, G. & Morgan, J. A. Mapping photoautotrophic metabolism with isotopically nonstationary 13C flux analysis. Metab. Eng. 14, 185–185 (2012).

    CAS  Article  Google Scholar 

  4. 4

    You, L., Berla, B., He, L., Pakrasi, B. H. & Tang, Y. J. 13C-MFA delineates the photomixotrophic metabolism of Synechocystis sp. PCC 6803 under light- and carbon-sufficient conditions. Biotechnol. J. 9, 684–692 (2014).

    CAS  Article  Google Scholar 

  5. 5

    Ungerer, J. et al. Sustained photosynthetic conversion of CO2 to ethylene in recombinant cyanobacterium Synechocystis 6803. Energ. Environ. Sci. 5, 8998–9006 (2012).

    CAS  Article  Google Scholar 

  6. 6

    Sheehan, J. Engineering direct conversion of CO2 to biofuel. Nature Biotechnol. 27, 1128–1129 (2009).

    CAS  Article  Google Scholar 

  7. 7

    Ducat, D. C., Way, J. C. & Silver, P. A. Engineering cyanobacteria to generate high-value products. Trends Biotechnol. 29, 95–103 (2011).

    CAS  Article  Google Scholar 

  8. 8

    Stephanopoulos, G. & Vallino, J. J. Network rigidity and metabolic engineering in metabolite overproduction. Science 252, 1675–1681 (1991).

    CAS  Article  Google Scholar 

  9. 9

    Melis, A. Carbon partitioning in photosynthesis. Curr. Opin. Chem. Biol. 17, 453–456 (2013).

    CAS  Article  Google Scholar 

  10. 10

    Davies, F. K., Work, V. H., Beliaev, A. S. & Posewitz, M. C. Engineering limonene and bisabolene production in wild type and a glycogen-deficient mutant of Synechococcus sp. PCC 7002. Front. Bioeng. Biotechnol. 2, 21 (2014).

    Article  Google Scholar 

  11. 11

    Guerrero, F., Carbonell, V., Cossu, M., Correddu, D. & Jones, P. R. Ethylene synthesis and regulated expression of recombinant protein in Synechocystis sp PCC 6803. PLoS ONE 7, e50470 (2012).

    CAS  Article  Google Scholar 

  12. 12

    Zhu, T., Xie, X. M., Li, Z. M., Tan, X. M. & Lu, X. F. Enhancing photosynthetic production of ethylene in genetically engineered Synechocystis sp PCC 6803. Green Chem. 17, 421–434 (2015).

    CAS  Article  Google Scholar 

  13. 13

    Jazmin, L. J. & Young, J. D. Isotopically nonstationary 13C metabolic flux analysis. Syst. Metab. Eng. Methods Mol. Biol. 985, 367–390 (2013).

    CAS  Article  Google Scholar 

  14. 14

    Cooley, J. W., Howitt, C. A. & Vermaas, W. F. J. Succinate: quinol oxidoreductases in the cyanobacterium Synechocystis sp strain PCC 6803: presence and function in metabolism and electron transport. J. Bacteriol. 182, 714–722 (2000).

    CAS  Article  Google Scholar 

  15. 15

    Cooley, J. W. & Vermaas, W. F. J. Succinate dehydrogenase and other respiratory pathways in thylakoid membranes of Synechocystis sp strain PCC 6803: capacity comparisons and physiological function. J. Bacteriol. 183, 4251–4258 (2001).

    CAS  Article  Google Scholar 

  16. 16

    Fukuda, H. et al. Two reactions are simultaneously catalyzed by a single enzyme: the arginine-dependent simultaneous formation of two products, ethylene and succinate, from 2-oxoglutarate by an enzyme from Pseudomonas syringae. Biochem. Biophys. Res. Commun. 188, 483–489 (1992).

    CAS  Article  Google Scholar 

  17. 17

    Labarre, J., Thuriaux, P. & Chauvat, F. Genetic analysis of amino acid transport in the facultatively heterotrophic cyanobacterium Synechocystis sp strain 6803. J. Bacteriol. 169, 4668–4673 (1987).

    CAS  Article  Google Scholar 

  18. 18

    Quintero, M. J., Montesinos, M. L., Herrero, A. & Flores, E. Identification of genes encoding amino acid permeases by inactivation of selected ORFs from the Synechocystis genomic sequence. Genome Res. 11, 2034–2040 (2001).

    CAS  Article  Google Scholar 

  19. 19

    Young, J. D. INCA: a computational platform for isotopically non-stationary metabolic flux analysis. Bioinformatics 30, 1333–1335 (2014).

    CAS  Article  Google Scholar 

  20. 20

    Ducat, D. C., Avelar-Rivas, J. A., Way, J. C. & Silver, P. A. Rerouting carbon flux to enhance photosynthetic productivity. Appl. Environ. Microb. 78, 2660–2668 (2012).

    CAS  Article  Google Scholar 

  21. 21

    Liu, X. Y., Sheng, J. & Curtiss, R. Fatty acid production in genetically modified cyanobacteria. Proc. Natl Acad. Sci. USA 108, 6899–6904 (2011).

    CAS  Article  Google Scholar 

  22. 22

    Deng, M. D. & Coleman, J. R. Ethanol synthesis by genetic engineering in cyanobacteria. Appl. Environ. Microb. 65, 523–528 (1999).

    CAS  Google Scholar 

  23. 23

    Lan, E. I. & Liao, J. C. ATP drives direct photosynthetic production of 1-butanol in cyanobacteria. Proc. Natl Acad. Sci. USA 109, 6018–6023 (2012).

    CAS  Article  Google Scholar 

  24. 24

    Angermayr, S. A., Paszota, M. & Hellingwerf, K. J. Engineering a cyanobacterial cell factory for production of lactic acid. Appl. Environ. Microb. 78, 7098–7106 (2012).

    CAS  Article  Google Scholar 

  25. 25

    Sweetlove, L. J., Beard, K. F. M., Nunes-Nesi, A., Fernie, A. R. & Ratcliffe, R. G. Not just a circle: flux modes in the plant TCA cycle. Trends Plant Sci. 15, 462–470 (2010).

    CAS  Article  Google Scholar 

  26. 26

    Zhang, S. Y. & Bryant, D. A. The tricarboxylic acid cycle in cyanobacteria. Science 334, 1551–1553 (2011).

    CAS  Article  Google Scholar 

  27. 27

    Xiong, W., Brune, D. & Vermaas, W. F. J. The gamma-aminobutyric acid shunt contributes to closing the tricarboxylic acid cycle in Synechocystis sp PCC 6803. Mol. Microbiol. 93, 786–796 (2014).

    CAS  Article  Google Scholar 

  28. 28

    Lopez-Bucio, J., Nieto-Jacobo, M. F., Ramirez-Rodriguez, V. & Herrera-Estrella, L. Organic acid metabolism in plants: from adaptive physiology to transgenic varieties for cultivation in extreme soils. Plant Sci. 160, 1–13 (2000).

    CAS  Article  Google Scholar 

  29. 29

    Nunes-Nesi, A. et al. Enhanced photosynthetic performance and growth as a consequence of decreasing mitochondrial malate dehydrogenase activity in transgenic tomato plants. Plant Physiol. 137, 611–622 (2005).

    CAS  Article  Google Scholar 

  30. 30

    Nunes-Nesi, A., Araujo, W. L. & Fernie, A. R. Targeting mitochondrial metabolism and machinery as a means to enhance photosynthesis. Plant Physiol. 155, 101–107 (2011).

    CAS  Article  Google Scholar 

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Acknowledgements

This work is supported by the National Renewable Energy Laboratory Director's Fellowship (W.X.), and the DOE Energy Efficiency and Renewable Energy (EERE) BioEnergy Technologies Office (J.Y., B.W.), EERE Fuel Cell Technologies Office (P.C.M.), and DOE Office of Science BER grant DE-SC0008628 (J.A.M.). We are grateful to Jamey D. Young of Vanderbilt University for providing software and technical assistance on 13C metabolic modelling, and to Maria Ghirardi, Carrie Eckert and William Michener for helpful discussion or assistance with LC–MS equipment.

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W.X., J.A.M., P.C.M. and J.Y. conceived the idea, and edited the manuscript. J.U. constructed the strains. B.W. analysed the Efe protein levels. W.X. designed and performed the experiments, analysed data and wrote most of the manuscript.

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Correspondence to Jianping Yu.

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The authors declare no competing financial interests.

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Xiong, W., Morgan, J., Ungerer, J. et al. The plasticity of cyanobacterial metabolism supports direct CO2 conversion to ethylene. Nature Plants 1, 15053 (2015). https://doi.org/10.1038/nplants.2015.53

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