The transcriptional activator NtrC controls the expression and activity of glutamine synthetase in Herbaspirillum seropedicae.
The role of the Ntr system in Herbaspirillum seropedicae was determined via ntrB and ntrC mutants. Three phenotypes were identified in these mutants: Nif(-), deficiency in growth using nitrate, and low glutamine synthetase (GS) activity. All phenotypes were restored by the plasmid pKRT1 containing the intact glnA, ntrB and ntrC genes of H. seropedicae. The promoter region of glnA was subcloned into a beta-galactosidase fusion vector and the results suggested that NtrC positively regulates the glnA promoter in response to low nitrogen. The H. seropedicae ntrC and ntrB mutant strains showed a deficiency of adenylylation/deadenylylation of GS, indicating that NtrC and NtrB are involved in both transcription and activity control of GS in this organism.
Persuhn
D C
DC
Departamento de Bioquímica, Universidade Federal do Paraná, C. Postal 19046, 81531-990, PR, Curitiba, Brazil.
Souza
E M
EM
Steffens
M B
MB
Pedrosa
F O
FO
Yates
M G
MG
Rigo
L U
LU
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D005798:Genes, Bacterial; D005822:Genetic Vectors; D005974:Glutamate-Ammonia Ligase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D006090:Gram-Negative Bacteria / Q000201:enzymology / Q000235:genetics*; D009154:Mutation; D009586:Nitrogen Fixation / Q000235:genetics; D051922:PII Nitrogen Regulatory Proteins; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors; D001616:beta-Galactosidase / Q000235:genetics
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D051922:PII Nitrogen Regulatory Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D001616:beta-Galactosidase; C081173:glutamine synthetase I; D005974:Glutamate-Ammonia Ligase