title: Glutamate synthase of Corynebacterium glutamicum is not essential for glutamate synthesis and is regulated by the nitrogen status.
abstract: The Corynebacterium glutamicum gltB and gltD genes, encoding the large (alpha) and small (beta) subunit of glutamate synthase (GOGAT), were investigated in this study. Using RT-PCR, a common transcript of gltB and gltD was shown. Reporter gene assays and Northern hybridization experiments revealed that transcription of this operon depends on nitrogen starvation. The expression of gltBD is under control of the global repressor protein AmtR as demonstrated by gel shift experiments and analysis of gltB transcription in an amtR deletion strain. In contrast to other bacteria, in C. glutamicum GOGAT plays no pivotal role; e.g. gltB and gltD inactivation did not result in growth defects when cells were grown in standard minimal medium and only a slight increase in the doubling time of the corresponding mutant strains was observed in the presence of limiting amounts of ammonia or urea. Additionally, mutant analyses revealed that GOGAT has no essential function in glutamate production by C. glutamicum.
authors.affiliation: Institut für Biochemie der Universität zu Köln, Zülpicher-Str. 47, D-50674 Köln, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Beckers
authors.forename: L
authors.initials: L
authors.lastname: Nolden
authors.forename: A
authors.initials: A
authors.lastname: Burkovski
mesh_terms: D001426:Bacterial Proteins; D015152:Blotting, Northern; D003352:Corynebacterium / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005970:Glutamate Synthase / Q000235:genetics* / Q000378:metabolism; D018698:Glutamic Acid / Q000096:biosynthesis*; D008744:Methylamines / Q000378:metabolism; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism*; D010957:Plasmids; D021122:Protein Subunits; D012097:Repressor Proteins / Q000502:physiology; D014158:Transcription, Genetic
chemical_list: C414398:AmtR protein, Corynebacterium glutamicum; D001426:Bacterial Proteins; D008744:Methylamines; D021122:Protein Subunits; D012097:Repressor Proteins; D018698:Glutamic Acid; C027451:methylamine; D005970:Glutamate Synthase; D009584:Nitrogen