Affiliation:
1. Departamento de Microbiología y Genética, CSIC/Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
2. BASF-Aktiengesellschaft, GVF/C-A30, 67056 Ludwigshafen, Germany
Abstract
ABSTRACT
Purine nucleotides are essential precursors for living organisms because they are involved in many important processes, such as nucleic acid synthesis, energy supply, and the biosynthesis of several amino acids and vitamins such as riboflavin. GTP is the immediate precursor for riboflavin biosynthesis, and its formation through the purine pathway is subject to several regulatory mechanisms in different steps. Extracellular purines repress the transcription of most genes required for de novo ATP and GTP synthesis. Additionally, three enzymes of the pathway, phosphoribosyl pyrophosphate (PRPP) amidotransferase, adenylosuccinate synthetase, and IMP dehydrogenase, are subject to feedback inhibition by their end products. Here we report the characterization and manipulation of the committed step in the purine pathway of the riboflavin overproducer
Ashbya gossypii
. We report that phosphoribosylamine biosynthesis in
A. gossypii
is negatively regulated at the transcriptional level by extracellular adenine. Furthermore, we show that ATP and GTP exert a strong inhibitory effect on the PRPP amidotransferase from
A. gossypii
. We constitutively overexpressed the Ag
ADE4
gene encoding PRPP amidotransferase in
A. gossypii
, thereby abolishing the adenine-mediated transcriptional repression. In addition, we replaced the corresponding residues (aspartic acid
310
, lysine
333
, and alanine
417
) that have been described to be important for PRPP amidotransferase feedback inhibition in other organisms by site-directed mutagenesis. With these manipulations, we managed to enhance metabolic flow through the purine pathway and to increase the production of riboflavin in the triple mutant strain 10-fold (228 mg/liter).
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
97 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献