Engineering Escherichia coli to overproduce aromatic amino acids and derived compounds

Abstract

The production of aromatic amino acids using fermentation processes with recombinant microorganisms can be an advantageous approach to reach their global demands. In addition, a large array of compounds with alimentary and pharmaceutical applications can potentially be synthesized from intermediates of this metabolic pathway. However, contrary to other amino acids and primary metabolites, the artificial channelling of building blocks from central metabolism towards the aromatic amino acid pathway is complicated to achieve in an efficient manner. The length and complex regulation of this pathway have progressively called for the employment of more integral approaches, promoting the merge of complementary tools and techniques in order to surpass metabolic and regulatory bottlenecks. As a result, relevant insights on the subject have been obtained during the last years, especially with genetically modified strains of Escherichia coli. By combining metabolic engineering strategies with developments in synthetic biology, systems biology and bioprocess engineering, notable advances were achieved regarding the generation, characterization and optimization of E. coli strains for the overproduction of aromatic amino acids, some of their precursors and related compounds. In this paper we review and compare recent successful reports dealing with the modification of metabolic traits to attain these objectives.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-014-0126-z) contains supplementary material, which is available to authorized users.

Amino acids production focusing on fermentation technologies – A review

“…Both can produce a broad spectrum of amino acids and several metabolic engineering alterations have been applied to improve their performance as amino acid producing organisms. Genetically modified C. glutamicum is used to produce lysine or glutamic acid (Becker et al, 2011) with high yields (up to 50 % w w -1 ) (Aoki et al, 2005), while E. coli has been modified to enable the production of the extremely interesting aromatic amino acids such as L-tryptophan, L-phenylalanine and L-tyrosine (Rodriguez et al, 2014a) (Table 3).…”

Glycolysis and Its Metabolic Engineering Applications

“…60,61 In E. coli, carbon storage regulator protein CsrA is global regulator that negatively impacts PEP synthesis by repressing pckA and ppsA while activating pykF, which channels flux away from PEP. 14,62,63 Repression or disruption of csrA will result in increased levels of PEP and increased production of aromatic amino acids. 15,61 Deletion of CsrA, additional overexpression of feedbackinhibitionresistant aromatic path way enzymes like AroG fbr (DAHP synthase) and TyrA fbr (chorismate mutase/prephenate dehydrogenase), and/or deletion of transcriptional repressor gene tyrR or trpR, will further enhance the production of aro matic compounds.…”

Inactivation of the PTS as a Strategy to Engineer the Production of Aromatic Metabolites in <b><i>Escherichia coli</i></b>

“…3 ) [Holms, 1996;Kameshita et al, 1978;Keseler et al, 2013;Sauer and Eikmanns, 2005]. This carbon flux distribution at the PEP node limits its availability for the high-yield production of several valuable metabolites derived from this precursor when E. coli uses glucose as the carbon source Flores et al, 1996;Gosset, 2005;Gosset et al, 1996;Rodriguez et al, 2014].…”

“…Glucose internalization by PTS consumes 50% of the PEP produced from the catabolism of glucose [Rodriguez et al, 2014]. In E. coli, PEP also participates in reactions catalyzed by PEP carboxylase ( ppc ; 16%), an enzyme that replenishes oxaloacetate in TCA, UDP-N-acetylglucosamine enolpyruvoyl transferase ( murA ; 16%) for the assembly of peptidoglycan, PYR kinases I and II ( pykF , pykA ; 15%) for the synthesis of PYR, and 2-dehydro-3-deoxyphosphoheptonate aldolase (DAHP) synthase isoenzymes ( aroF , aroG , aroH ; 3%) for the synthesis of aromatic compounds ( fig.…”