L-Glutamine as a nitrogen source for Corynebacterium glutamicum: derepression of the AmtR regulon and implications for nitrogen sensing.
Corynebacterium glutamicum, a Gram-positive soil bacterium employed in the industrial production of various amino acids, is able to use a number of different nitrogen sources, such as ammonium, urea or creatinine. This study shows that l-glutamine serves as an excellent nitrogen source for C. glutamicum and allows similar growth rates in glucose minimal medium to those in ammonium. A transcriptome comparison revealed that the nitrogen starvation response was elicited when glutamine served as the sole nitrogen source, meaning that the target genes of the global nitrogen regulator AmtR were derepressed. Subsequent growth experiments with a variety of mutants defective in nitrogen metabolism showed that glutamate synthase is crucial for glutamine utilization, while a putative glutaminase is dispensable under the experimental conditions used. The gltBD operon encoding the glutamate synthase is a member of the AmtR regulon. The observation that the nitrogen starvation response was elicited at high intracellular l-glutamine levels has implications for nitrogen sensing. In contrast with other Gram-positive and Gram-negative bacteria such as Bacillus subtilis, Salmonella enterica serovar Typhimurium and Klebsiella pneumoniae, a drop in glutamine concentration obviously does not serve as a nitrogen starvation signal in C. glutamicum.
Rehm
Nadine
N
Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany.
Georgi
Tobias
T
Institut für Biotechnologie 1, Forschungszentrum Jülich, D-52425 Jülich, Germany.
Hiery
Eva
E
Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany.
Degner
Ursula
U
Institut für Biotechnologie 1, Forschungszentrum Jülich, D-52425 Jülich, Germany.
Schmiedl
Alfred
A
Lehrstuhl für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany.
Burkovski
Andreas
A
Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany.
Bott
Michael
M
Institut für Biotechnologie 1, Forschungszentrum Jülich, D-52425 Jülich, Germany.
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D048230:Corynebacterium glutamicum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D003470:Culture Media; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005970:Glutamate Synthase / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism*; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics; D018085:Regulon; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*
C414398:AmtR protein, Corynebacterium glutamicum; D001426:Bacterial Proteins; D003470:Culture Media; D000644:Quaternary Ammonium Compounds; D012329:RNA, Bacterial; D012097:Repressor Proteins; D005973:Glutamine; D005970:Glutamate Synthase; D009584:Nitrogen