Activation of the Rhizobium leguminosarum glnII gene by NtrC is dependent on upstream DNA sequences.
The cloning and sequence determination is reported of the DNA region of Rhizobium leguminosarum coding for glutamine synthetase II (GSII). An open reading frame (ORF) encoding 326 amino acids was defined as the glnII gene on the basis of its similarity to other glnII genes and the ability of a DNA fragment carrying this ORF to complement the glutamine auxotrophy of a Klebsiella pneumoniae glnA mutant. We find that the glnII gene in R. leguminosarum is transcribed as a monocistronic unit from a single promoter, which shows structural features characteristic of rpoN (ntrA)-dependent promoters. In K. pneumoniae, such promoters require the ntrC and rpoN (ntrA) gene products for transcription. The intracellular level of glnII mRNA changes when R. leguminosarum is grown on different nitrogen sources, as expected for regulation by the nitrogen regulatory system. Promoter deletion analysis has shown that an extensive upstream DNA sequence (316 bp) is essential for in vivo activation of the glnII promoter in different biovars of R. leguminosarum. This DNA region requires a wild-type ntrC gene for activity and includes two conserved putative NtrC-binding site sequences. The results conclusively show that transcription from the R. leguminosarum glnII promoter is fully dependent on positive control by NtrC protein and on an upstream activator sequence (UAS).
International Institute of Genetics and Biophysics, CNR, Naples, Italy.
E J
EJ
Patriarca
M
M
Chiurazzi
G
G
Manco
A
A
Riccio
A
A
Lamberti
A
A
De Paolis
M
M
Rossi
R
R
Defez
M
M
Iaccarino
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D016384:Consensus Sequence; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005974:Glutamate-Ammonia Ligase / Q000235:genetics*; D007711:Klebsiella pneumoniae / Q000235:genetics; D008969:Molecular Sequence Data; D051922:PII Nitrogen Regulatory Proteins; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D016961:Rhizobium leguminosarum / Q000235:genetics*; D016415:Sequence Alignment; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D051922:PII Nitrogen Regulatory Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D005974:Glutamate-Ammonia Ligase