In vivo instability of chorismate causes substrate loss during fermentative production of aromatics

Authors

  • Gal Winter,

    Corresponding author
    1. Centre for Microbial Electrosynthesis (CEMES), University of Queensland, Brisbane, Australia
    • Correspondence to: G. Winter, Centre for Microbial Electrosynthesis (CEMES), Advanced Water Management Centre, Gehrmann Laboratories (Building 60–620), University of Queensland, Brisbane, Queensland 4072, Australia. E-mail: g.winter@uq.edu.au

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  • Nils J.H. Averesch,

    1. Centre for Microbial Electrosynthesis (CEMES), University of Queensland, Brisbane, Australia
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  • Dariela Nunez-Bernal,

    1. Australian Institute for Bioengineering and Nanotechnology (AIBN), University of Queensland, Brisbane, Australia
    2. Biotechnology Centre, Universidad San Sebastián, Santiago, Chile
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  • Jens O. Krömer

    1. Centre for Microbial Electrosynthesis (CEMES), University of Queensland, Brisbane, Australia
    2. Advanced Water Management Centre (AWMC), University of Queensland, Brisbane, Australia
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Abstract

Metabolic engineering of microbial strains to produce aromatic compounds deriving from the shikimate pathway is of great interest to the chemical industry as a more sustainable alternative for feedstock production. Chorismate is a significant intermediate in the shikimate pathway. In this study, the formation of phenylalanine and phenylpyruvate as by-products in strains engineered downstream of the chorismate node for increased aromatic production was explored in yeast fermentations. Tracer experiments showed that these compounds are synthesized de novo during fermentation, under conditions in which their synthesis was genetically blocked. Chorismate stability evaluation, as well as deletion mutation analysis throughout the phenylalanine biosynthesis pathway, suggested that this synthesis was a result of intracellular, non-enzymatic rearrangement of chorismate to phenylpyruvate via prephenate, which was followed by enzymatic transamination of phenylpyruvate to form phenylalanine. These results not only aid in the development of strain-engineering strategies to avoid the accumulation of by-products during fermentations aimed at increased aromatics production, but also deepen our understanding of yeast metabolism. Copyright © 2014 John Wiley & Sons, Ltd.

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