Book/Dissertation / PhD Thesis

FZJ-2021-03172

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png γ-Aminobutyrate as carbon and nitrogen source for Corynebacterium glutamicum and regulation of the catabolic genes by GabR

Zhu, L. (Corresponding author)FZJ*

2021
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-543-7

Please use a persistent id in citations: http://hdl.handle.net/2128/28459  urn:nbn:de:0001-2021081100

Abstract: Corynebacterium glutamicum is a Gram-positive soil bacterium widely used in theindustrial production of amino acids such as L-glutamate and L-lysine. C. glutamicumis able to use a variety of carbohydrates, alcohols and organic acids as singlesources of carbon and energy for growth and some also for amino acid production. Inthis thesis, further potential carbon sources were investigated whether they can beused for growth by C. glutamicum. γ-Aminobutyric acid (GABA) is a nonproteinogenicamino acid and widespread in nature from microorganisms to plantsand animals. C. glutamicum showed good growth with GABA as sole carbon andnitrogen source. Remarkably, ammonia and and to a lesser extent urea inhibitedgrowth on GABA, whereas L-glutamine stimulated it. Possible reasons for theseeffects were analyzed. Genome-wide expression analysis revealed that the gabTDPgenes encoding GABA transaminase, succinate semialdehyde dehydrogenase, andGABA permease, respectively, were highly induced in cells grown with GABA ascarbon source compared to glucose-grown cells. The corresponding proteinscatalyze GABA uptake, the transfer of the amino group to 2-oxoglutarate, and theoxidation of the resulting succinate semialdehyde to succinate. Transcriptionalactivation of the gabTDP genes was shown to be strictly dependent on thetranscriptional regulator GabR, which is encoded upstream of and divergent to gabT.A ΔgabR mutant failed to grow on GABA, but not with other carbon sources. Growthof the ΔgabR mutant on GABA could be restored by plasmid-based expression ofeither gabR or gabTDP. Reporter gene studies confirmed that expression of gabTDPis dependent on GabR and GABA. Glucose caused reduced expression of gabTDPpresumably via the cAMP-dependent global regulator GlxR. GabR belongs to thePucR family of transcriptional regulators. Purified GabR eluted as an octamer with anapparent mass of 420 kDa in size-exclusion chromatography and bound specificallyto two binding sites in the gabR-gabT intergenic region extending from -36 to -56 andfrom -67 to -87 upstream of the gabT transcriptional start site. These results uncovernew features of actinobacterial GABA utilization.

Note: Dissertation, Univ. Düsseldorf, 2020

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Contributing Institute(s):

1. Biotechnologie (IBG-1)

Research Program(s):

1. 2171 - Biological and environmental resources for sustainable use (POF4-217) (POF4-217)

Appears in the scientific report 2021

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Database coverage:
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