Relaxed rrn expression and amino acid requirement of a Corynebacterium glutamicum rel mutant defective in (p)ppGpp metabolism.
The stringent response in Corynebacterium glutamicum was investigated. Sets of rrn-cat fusions were constructed in their native chromosomal position to examine the effects of amino acid starvation in a rel(+) strain and a Deltarel mutant defective in (p)ppGpp metabolism. The expression of the six rrn operons in the rel(+) control was stringently regulated and reduced to 79% upon induction of amino acid starvation. The Deltarel mutant displayed a relaxed regulation and was unable to reduce the rrn expression under amino acid depletion conditions. In addition, the Deltarel mutant grew more slowly in minimal medium than a rel(+) control. This growth effect was restored by a plasmid-encoded copy of rel or, alternatively, by supplementation of the minimal medium with the amino acid mixture casamino acids. In particular, the Deltarel strain of C. glutamicum displayed a requirement for the amino acids histidine and serine.
Tauch
A
A
Department of Genetics, University of Bielefeld, P.O. Box 100131, D-33501 Bielefeld, Germany.
Wehmeier
L
L
Götker
S
S
Pühler
A
A
Kalinowski
J
J
D000596:Amino Acids / Q000378:metabolism*; D019677:Artificial Gene Fusion; D003352:Corynebacterium / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006158:Guanosine Pentaphosphate / Q000378:metabolism*; D009154:Mutation; D011755:Pyrophosphatases / Q000235:genetics* / Q000378:metabolism; D012694:Serine / Q000031:analogs & derivatives / Q000494:pharmacology; D012407:rRNA Operon
D000596:Amino Acids; D003470:Culture Media; C028002:serine hydroxamate; D006158:Guanosine Pentaphosphate; D012694:Serine; C027627:guanosine-3',5'-bis(diphosphate) 3'-pyrophosphatase; D011755:Pyrophosphatases