TY  - JOUR
AU  - Zhu, Lingfeng
AU  - Mack, Christina
AU  - Wirtz, Astrid
AU  - Kranz, Angela
AU  - Polen, Tino
AU  - Baumgart, Meike
AU  - Bott, Michael
TI  - Regulation of γ-Aminobutyrate (GABA) Utilization in Corynebacterium glutamicum by the PucR-Type Transcriptional Regulator GabR and by Alternative Nitrogen and Carbon Sources
JO  - Frontiers in microbiology
VL  - 11
SN  - 1664-302X
CY  - Lausanne
PB  - Frontiers Media
M1  - FZJ-2020-04175
SP  - 544045
PY  - 2020
N1  - Biotechnologie 1
AB  - γ-Aminobutyric acid (GABA) is a non-proteinogenic amino acid mainly formed by decarboxylation of L-glutamate and is widespread in nature from microorganisms to plants and animals. In this study, we analyzed the regulation of GABA utilization by the Gram-positive soil bacterium Corynebacterium glutamicum, which serves as model organism of the phylum Actinobacteria. We show that GABA usage is subject to both specific and global regulatory mechanisms. Transcriptomics revealed that the gabTDP genes encoding GABA transaminase, succinate semialdehyde dehydrogenase, and GABA permease, respectively, were highly induced in GABA-grown cells compared to glucose-grown cells. Expression of the gabTDP genes was dependent on GABA and the PucR-type transcriptional regulator GabR, which is encoded divergently to gabT. A ΔgabR mutant failed to grow with GABA, but not with glucose. Growth of the mutant on GABA was restored by plasmid-based expression of gabR or of gabTDP, indicating that no further genes are specifically required for GABA utilization. Purified GabR (calculated mass 55.75 kDa) formed an octamer with an apparent mass of 420 kDa and bound to two inverted repeats in the gabR-gabT intergenic region. Glucose, gluconate, and myo-inositol caused reduced expression of gabTDP, presumably via the cAMP-dependent global regulator GlxR, for which a binding site is present downstream of the gabT transcriptional start site. C. glutamicum was able to grow with GABA as sole carbon and nitrogen source. Ammonium and, to a lesser extent, urea inhibited growth on GABA, whereas L-glutamine stimulated it. Possible mechanisms for these effects are discussed.
LB  - PUB:(DE-HGF)16
C6  - pmid:33193127
UR  - <Go to ISI:>//WOS:000587701900001
DO  - DOI:10.3389/fmicb.2020.544045
UR  - https://juser.fz-juelich.de/record/885911
ER  -