Disease relevance of glnB

• The glnB region of the Escherichia coli chromosome [1].
• The glnB gene of Klebsiella pneumoniae, which encodes the nitrogen regulation protein PII, has been cloned and sequenced [2].
• Potential homologues of glnB encoding polypeptides extremely similar in sequence to PII were identified upstream of published sequences of the glutamine synthetase structural gene (glnA) in Rhizobium leguminosarum, Bradyrhizobium japonicum and Azospirillum brasilense [2].
• The glnB gene was cloned from S. hygroscopicus DNA by complementation in an Escherichia coli glutamine auxotrophic mutant (glnA). glnB was subcloned in Streptomyces plasmids by insertion into pIJ486 (pMSG3) and pIJ702 (pMSG5) [3].
• Southern blot hybridization experiments showed that sequences similar to glnB were present in all of the five other Streptomyces species tested, as well as Frankia species [3].

High impact information on glnB

• The complete nucleotide sequence of the glnB gene was determined and parts of the deduced amino acid sequence were confirmed by the results of amino acid sequence analysis of peptides [4].
• Nucleotide sequence analysis of the upstream region showed no obvious sites for the binding of RNA polymerase, indicating that the glnB gene is a part of an as yet unidentified operon [4].
• A procedure was developed to purify large quantities of PII protein from an Escherichia coli strain which contains a multicopy plasmid harboring the structural gene of PII (the glnB gene) [4].
• We observe that glnB ntrC and glnB glnK ntrC mutant strains accumulate high levels of intracellular 2-oxoglutarate under conditions of nitrogen excess [5].
• The PII protein, encoded by glnB, is known to interact with three bifunctional signal transducing enzymes (uridylyltransferase/uridylyl-removing enzyme, adenylyltransferase, and the kinase/phosphatase nitrogen regulator II [NRII or NtrB]) and three small-molecule effectors, glutamate, 2-ketoglutarate, and ATP [6].

Chemical compound and disease context of glnB

• The glnB gene from Bradyrhizobium japonicum, the endosymbiont of soybeans (Glycine max), was isolated and sequenced, and its expression was examined under various culture conditions and in soybean nodules [7].

Biological context of glnB

• We present sequences of the glnB gene of Escherichia coli and of two open reading frames (ORFs) located directly upstream of glnB and transcribed in the same direction [1].
• Identification of the Klebsiella pneumoniae glnB gene: nucleotide sequence of wild-type and mutant alleles [2].
• The pur operator in glnB is located between two major transcription start sites that were located by primer extension mapping [8].
• The truncated proteins were also able to restore nif gene expression to a glnB mutant, suggesting that PII is required to activate NifA by preventing the inhibitory effect of its N-terminal domain under conditions of nitrogen fixation [9].
• Mutations in glnB, nifR1 (ntrC), and NifR4 (ntrA encoding sigma 54) had no influence on put gene expression [10].

Associations of glnB with chemical compounds

• The sequences of a glnB mutation which causes glutamine auxotrophy and of a Tn5 induced Gln+ suppressor of this mutation were also determined [2].

Other interactions of glnB

• The product of neither ORF-1 nor ORF-2 is necessary for the ability of PII, the product of glnB, to bring about the repression of glutamine synthetase in response to nitrogen excess [1].
• Moreover, disruption of both the E. coli glnB and ntrC genes resulted in a complete loss of nitrogen regulation of NifA activity by NifL [5].
• The A. brasilense NtrC protein activated transcription of glnB-lacZ fusions in the heterologous genetic background of Escherichia coli [11].

Analytical, diagnostic and therapeutic context of glnB

• We constructed 15 conservative alterations of PII by site-specific mutagenesis of glnB and also isolated three random glnB mutants affecting nitrogen regulation [6].

References