PortEco logo

PMID:19918073

From EcoliWiki
Jump to: navigation, search

Contents

Citation

Zhang, X, Jantama, K, Moore, JC, Jarboe, LR, Shanmugam, KT and Ingram, LO (2009) Metabolic evolution of energy-conserving pathways for succinate production in Escherichia coli. Proc. Natl. Acad. Sci. U.S.A. 106:20180-5

Abstract

During metabolic evolution to improve succinate production in Escherichia coli strains, significant changes in cellular metabolism were acquired that increased energy efficiency in two respects. The energy-conserving phosphoenolpyruvate (PEP) carboxykinase (pck), which normally functions in the reverse direction (gluconeogenesis; glucose repressed) during the oxidative metabolism of organic acids, evolved to become the major carboxylation pathway for succinate production. Both PCK enzyme activity and gene expression levels increased significantly in two stages because of several mutations during the metabolic evolution process. High-level expression of this enzyme-dominated CO(2) fixation and increased ATP yield (1 ATP per oxaloacetate). In addition, the native PEP-dependent phosphotransferase system for glucose uptake was inactivated by a mutation in ptsI. This glucose transport function was replaced by increased expression of the GalP permease (galP) and glucokinase (glk). Results of deleting individual transport genes confirmed that GalP served as the dominant glucose transporter in evolved strains. Using this alternative transport system would increase the pool of PEP available for redox balance. This change would also increase energy efficiency by eliminating the need to produce additional PEP from pyruvate, a reaction that requires two ATP equivalents. Together, these changes converted the wild-type E. coli fermentation pathway for succinate into a functional equivalent of the native pathway that nature evolved in succinate-producing rumen bacteria.

Links

PubMed PMC2777959 Online version:10.1073/pnas.0905396106

Keywords

Adenosine Triphosphate/metabolism; Calcium-Binding Proteins/metabolism; Carbon Dioxide/metabolism; Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Evolution, Molecular; Fermentation; Gene Expression Regulation, Enzymologic/genetics; Industrial Microbiology/methods; Monosaccharide Transport Proteins/genetics; Monosaccharide Transport Proteins/metabolism; Mutation/genetics; Periplasmic Binding Proteins/metabolism; Phosphoenolpyruvate Carboxykinase (ATP)/metabolism; Phosphoenolpyruvate Sugar Phosphotransferase System/genetics; Succinic Acid/metabolism

Significance

You can help EcoliWiki by summarizing why this paper is useful

Useful Materials and Methods

You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.

Annotations

Gene product Qualifier GO ID GO term name Evidence Code with/from Aspect Notes Status

EcoliWiki Links

Add links to pages that link here (e.g. gene, product, method pages)

See also

References

See Help:References for how to manage references in EcoliWiki.