Expanding metabolism for biosynthesis of nonnatural alcohols

Department of Chemical and Biomolecular Engineering and Chemistry, University of California, Los Angeles, CA 90095, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 01/2009; 105(52):20653-8. DOI: 10.1073/pnas.0807157106
Source: PubMed

ABSTRACT Nature uses a limited set of metabolites to perform all of the biochemical reactions. To increase the metabolic capabilities of biological systems, we have expanded the natural metabolic network, using a nonnatural metabolic engineering approach. The branched-chain amino acid pathways are extended to produce abiotic longer chain keto acids and alcohols by engineering the chain elongation activity of 2-isopropylmalate synthase and altering the substrate specificity of downstream enzymes through rational protein design. When introduced into Escherichia coli, this nonnatural biosynthetic pathway produces various long-chain alcohols with carbon number ranging from 5 to 8. In particular, we demonstrate the feasibility of this approach by optimizing the biosynthesis of the 6-carbon alcohol, (S)-3-methyl-1-pentanol. This work demonstrates an approach to build artificial metabolism beyond the natural metabolic network. Nonnatural metabolites such as long chain alcohols are now included in the metabolite family of living systems.

1 Bookmark
  • Source
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The filamentous fungus, Asperigillus carbonarius, is able to produce a series of hydrocarbons in liquid culture using lignocellulosic biomasses, such as corn stover and switch grass as carbon source. The hydrocarbons produced by the fungus show similarity to jet fuel composition and might have industrial application. The production of hydrocarbons was found to be dependent on type of media used. Therefore, ten different carbon sources (oat meal, wheat bran, glucose, carboxymethyl cellulose, avicel, xylan, corn stover, switch grass, pretreated corn stover, and pretreated switch grass) were tested to identify the maximum number and quantity of hydrocarbons produced. Several hydrocarbons were produced include undecane, dodecane, tetradecane, hexadecane 2,4-dimethylhexane, 4-methylheptane, 3-methyl-1-butanol, ethyl benzene, o-xylene. Oatmeal was found to be the carbon source resulting in the largest amounts of hydrocarbon products. The production of fungal hydrocarbons, especially from lignocellulosic biomasses, holds a great potential for future biofuel production whenever our knowledge on regulators and pathways increases. Copyright © 2015 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.
    Fungal Biology 01/2015; 119(4). DOI:10.1016/j.funbio.2015.01.001 · 2.14 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Photobiological hydrogen production is an attractive, carbon-neutral means to convert solar energy to hydrogen. We build on previous research improving the Alteromonas macleodii "Deep Ecotype" [NiFe] hydrogenase, and report progress towards creating an artificial electron transfer pathway to supply the hydrogenase with electrons necessary for hydrogen production. Ferredoxin is the first soluble electron transfer mediator to receive high-energy electrons from photosystem I, and bears an electron with sufficient potential to efficiently reduce protons. Thus, we engineered a hydrogenase-ferredoxin fusion that also contained several other modifications. In addition to the C-terminal ferredoxin fusion, we truncated the C-terminus of the hydrogenase small subunit, identified as the available terminus closer to the electron transfer region. We also neutralized an anionic patch surrounding the interface Fe-S cluster to improve transfer kinetics with the negatively charged ferredoxin. Initial screening showed the enzyme tolerated both truncation and charge neutralization on the small subunit ferredoxin-binding face. While the enzyme activity was relatively unchanged using the substrate methyl viologen, we observed a marked improvement from both the ferredoxin fusion and surface modification using only dithionite as an electron donor. Combining ferredoxin fusion and surface charge modification showed progressively improved activity in an in vitro assay with purified enzyme.
    International Journal of Molecular Sciences 01/2015; 16(1):2020-33. DOI:10.3390/ijms16012020 · 2.46 Impact Factor

Full-text (2 Sources)

Available from
Jul 3, 2014