Identification and Characterization of -Aminobutyric Acid Uptake System GabPCg (NCgl0464) in Corynebacterium glutamicum

State Key Laboratory of Microbial Resourcesa and Department of Industrial Microbiology and Biotechnology, Beijing, People’s Republic of China.
Applied and Environmental Microbiology (Impact Factor: 3.67). 02/2012; 78(8):2596-601. DOI: 10.1128/AEM.07406-11
Source: PubMed


Corynebacterium glutamicum is widely used for industrial production of various amino acids and vitamins, and there is growing interest in engineering
this bacterium for more commercial bioproducts such as γ-aminobutyric acid (GABA). In this study, a C. glutamicum GABA-specific transporter (GabPCg) encoded by ncgl0464 was identified and characterized. GabPCg plays a major role in GABA uptake and is essential to C. glutamicum growing on GABA. GABA uptake by GabPCg was weakly competed by l-Asn and l-Gln and stimulated by sodium ion (Na+). The Km and Vmax values were determined to be 41.1 ± 4.5 μM and 36.8 ± 2.6 nmol min−1 (mg dry weight [DW])−1, respectively, at pH 6.5 and 34.2 ± 1.1 μM and 67.3 ± 1.0 nmol min−1 (mg DW)−1, respectively, at pH 7.5. GabPCg has 29% amino acid sequence identity to a previously and functionally identified aromatic amino acid transporter (TyrP) of
Escherichia coli but low identities to the currently known GABA transporters (17% and 15% to E. coli GabP and Bacillus subtilis GabP, respectively). The mutant RES167 Δncgl0464/pGXKZ9 with the GabPCg deletion showed 12.5% higher productivity of GABA than RES167/pGXKZ9. It is concluded that GabPCg represents a new type of GABA transporter and is potentially important for engineering GABA-producing C. glutamicum strains.

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Available from: Ning-Yi Zhou, Aug 09, 2015
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    • "Using heterologous expression of Lactobacillus brevis genes for: i) glutamate decarboxylase (gadB2) to catalyze glutamate decarboxylation to GABA, ii) L-glutamate/GABA antiporter gene gadC and iii) the transcriptional regulator gene gadR, Shi and Li constructed a strain that could produce more than 2 g l-1 GABA in 72 hours [64]. Zhao et al. reported the GABA transporter in C. glutamicum responsible for its uptake and were able to show that disruption of its gene led to increased GABA production [65]. Production of GABA using C. glutamicum has the advantage that it is independent of external glutamate supply and complex media ingredients, which is the case when using lactic-acid bacteria (LAB) for its production. "
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    ABSTRACT: Corynebacterium glutamicum is well known as the amino acid-producing workhorse of fermentation industry, being used for multi-million-ton scale production of glutamate and lysine for more than 60 years. However, it is only recently that extensive research has focused on engineering it beyond the scope of amino acids. Meanwhile, a variety of corynebacterial strains allows access to alternative carbon sources and/or allows production of a wide range of industrially relevant compounds. Some of these efforts set new standards in terms of titers and productivities achieved whereas others represent a proof-of-principle. These achievements manifest the position of C. glutamicum as an important industrial microorganism with capabilities far beyond the traditional amino acid production. In this review we focus on the state of the art of metabolic engineering of C. glutamicum for utilization of alternative carbon sources, (e.g. coming from wastes and unprocessed sources), and construction of C. glutamicum strains for production of new products such as diamines, organic acids and alcohols.
    Full-text · Article · Oct 2012 · Computational and Structural Biotechnology Journal
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    ABSTRACT: The transcriptional regulator GlxR has been characterised as a global hub within the gene-regulatory network of Corynebacterium glutamicum. Chromatin immunoprecipitation with a specific anti-GlxR antibody and subsequent high-throughput sequencing (ChIP-seq) was applied to C. glutamicum to get new in vivo insights into the gene composition of the GlxR regulon. In a comparative approach C. glutamicum cells were grown with either glucose or acetate as the sole carbon source prior to immunoprecipitation. High-througput sequencing resulted in 69 million reads and 2.6 Gb of genomic information. After mapping of these sequence data on the genome sequence of C. glutamicum, 107 enriched DNA fragments were detected from cells grown with glucose as carbon source. GlxR binding sites were identified in the sequence of 79 enriched DNA fragments, of which 21 sites were not previously reported. Electrophoretic mobility shift assays with 40-mer oligomers covering the GlxR binding sites were performed for validation of the in vivo results. The detection of new binding sites confirmed the role of GlxR as a regulator of carbon source metabolism and energy conversion, but additionally revealed binding of GlxR in front of the 6C non-coding RNA gene and to non-canonical DNA binding sites within protein-coding regions. The present study underlines the dynamics within the GlxR regulon by identifying in vivo targets during growth on glucose and contributes to the expansion of knowledge of this important transcriptional regulator.
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