title: Identification and characterization of the main beta-alanine uptake system in Escherichia coli.
abstract: In Escherichia coli, beta-alanine is a direct precursor in the biosynthesis of pantothenic acid (vitamin B5). Although a sufficient beta-alanine supply is crucial for biotechnological vitamin B5 production, nothing was known about beta-alanine transport in E. coli until now. The aim of this work was the characterization of beta-alanine transport by E. coli and the identification and overexpression of the corresponding carrier-encoding gene for the rational improvement of pantothenic acid-producing strains. beta-Alanine uptake was found to be an active process catalyzed by the amino acid carrier CycA. The corresponding gene was cloned and overexpressed, resulting in an increase in the uptake rate, compared with the wild type. In all tested strains, this overexpression led to a strong sensitivity to beta-alanine, but not to the other CycA substrates, such as L-alanine, D-alanine, and glycine. This prevented a direct application for the improvement of pantothenic acid-producing strains by an enhanced precursor supply.
authors.affiliation: Institut für Biochemie, Universität Köln, Zülpicher-Strasse 47, 50674, Cologne, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Schneider
authors.forename: Reinhard
authors.initials: R
authors.lastname: Krämer
authors.forename: Andreas
authors.initials: A
authors.lastname: Burkovski
mesh_terms: D000409:Alanine / Q000378:metabolism; D026905:Amino Acid Transport Systems / Q000235:genetics*; D001693:Biological Transport, Active; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005998:Glycine / Q000378:metabolism; D006131:Growth Inhibitors / Q000378:metabolism / Q000494:pharmacology; D010205:Pantothenic Acid / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015091:beta-Alanine / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D026905:Amino Acid Transport Systems; D029968:Escherichia coli Proteins; D006131:Growth Inhibitors; D011994:Recombinant Proteins; D015091:beta-Alanine; D010205:Pantothenic Acid; D000409:Alanine; D005998:Glycine