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Development and application of an arabinose-inducible expression system by facilitating inducer uptake in Corynebacterium glutamicum.

ABSTRACT: Corynebacterium glutamicum is currently used for the industrial production of a variety of biological materials. Many available inducible expression systems in this species use lac-derived promoters from Escherichia coli that exhibit much lower levels of inducible expression and leaky basal expression. We developed an arabinose-inducible expression system that contains the L-arabinose regulator AraC, the P(BAD) promoter from the araBAD operon, and the L-arabinose transporter AraE, all of which are derived from E. coli. The level of inducible P(BAD)-based expression could be modulated over a wide concentration range from 0.001 to 0.4% L-arabinose. This system tightly controlled the expression of the uracil phosphoribosyltransferase without leaky expression. When the gene encoding green fluorescent protein (GFP) was under the control of P(BAD) promoter, flow cytometry analysis showed that GFP was expressed in a highly homogeneous profile throughout the cell population. In contrast to the case in E. coli, P(BAD) induction was not significantly affected in the presence of different carbon sources in C. glutamicum, which makes it useful in fermentation applications. We used this system to regulate the expression of the odhI gene from C. glutamicum, which encodes an inhibitor of ?-oxoglutarate dehydrogenase, resulting in high levels of glutamate production (up to 13.7 mM) under biotin nonlimiting conditions. This system provides an efficient tool available for molecular biology and metabolic engineering of C. glutamicum.

SUBMITTER: Zhang Y

PROVIDER: S-EPMC3406113 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature

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Development and application of an arabinose-inducible expression system by facilitating inducer uptake in Corynebacterium glutamicum.

Zhang Yun Y Shang Xiuling X Lai Shujuan S Zhang Guoqiang G Liang Yong Y Wen Tingyi T

Applied and environmental microbiology 20120608 16

Corynebacterium glutamicum is currently used for the industrial production of a variety of biological materials. Many available inducible expression systems in this species use lac-derived promoters from Escherichia coli that exhibit much lower levels of inducible expression and leaky basal expression. We developed an arabinose-inducible expression system that contains the L-arabinose regulator AraC, the P(BAD) promoter from the araBAD operon, and the L-arabinose transporter AraE, all of which a ...[more]

PMID: 22685153

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Project description:To date, no information has been made available on the genetic traits that lead to increased carbon flow into the fatty acid biosynthetic pathway of Corynebacterium glutamicum. To develop basic technologies for engineering, we employed an approach that begins by isolating a fatty acid-secreting mutant without depending on mutagenic treatment. This was followed by genome analysis to characterize its genetic background. The selection of spontaneous mutants resistant to the palmitic acid ester surfactant Tween 40 resulted in the isolation of a desired mutant that produced oleic acid, suggesting that a single mutation would cause increased carbon flow down the pathway and subsequent excretion of the oversupplied fatty acid into the medium. Two additional rounds of selection of spontaneous cerulenin-resistant mutants led to increased production of the fatty acid in a stepwise manner. Whole-genome sequencing of the resulting best strain identified three specific mutations (fasR20, fasA63(up), and fasA2623). Allele-specific PCR analysis showed that the mutations arose in that order. Reconstitution experiments with these mutations revealed that only fasR20 gave rise to oleic acid production in the wild-type strain. The other two mutations contributed to an increase in oleic acid production. Deletion of fasR from the wild-type strain led to oleic acid production as well. Reverse transcription-quantitative PCR analysis revealed that the fasR20 mutation brought about upregulation of the fasA and fasB genes encoding fatty acid synthases IA and IB, respectively, by 1.31-fold ± 0.11-fold and 1.29-fold ± 0.12-fold, respectively, and of the accD1 gene encoding the ?-subunit of acetyl-CoA carboxylase by 3.56-fold ± 0.97-fold. On the other hand, the fasA63(up) mutation upregulated the fasA gene by 2.67-fold ± 0.16-fold. In flask cultivation with 1% glucose, the fasR20 fasA63(up) fasA2623 triple mutant produced approximately 280 mg of fatty acids/liter, which consisted mainly of oleic acid (208 mg/liter) and palmitic acid (47 mg/liter).

Dataset Information

Development and application of an arabinose-inducible expression system by facilitating inducer uptake in Corynebacterium glutamicum.

Publications

Development and application of an arabinose-inducible expression system by facilitating inducer uptake in Corynebacterium glutamicum.

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