Inactivation of gltB Abolishes Expression of the Assimilatory Nitrate Reductase Gene (nasB) in Pseudomonas putida KT2442
AUTOR(ES)
Eberl, Leo
FONTE
American Society for Microbiology
RESUMO
By using mini-Tn5 transposon mutagenesis, random transcriptional fusions of promoterless bacterial luciferase, luxAB, to genes of Pseudomonas putida KT2442 were generated. Insertion mutants that responded to ammonium deficiency by induction of bioluminescence were selected. The mutant that responded most strongly was genetically analyzed and is demonstrated to bear the transposon within the assimilatory nitrate reductase gene (nasB) of P. putida KT2442. Genetic evidence as well as sequence analyses of the DNA regions flanking nasB suggest that the genes required for nitrate assimilation are not clustered. We isolated three second-site mutants in which induction of nasB expression was completely abolished under nitrogen-limiting conditions. Nucleotide sequence analysis of the chromosomal junctions revealed that in all three mutants the secondary transposon had inserted at different sites in the gltB gene of P. putida KT2442 encoding the major subunit of the glutamate synthase. A detailed physiological characterization of the gltB mutants revealed that they are unable to utilize a number of potential nitrogen sources, are defective in the ability to express nitrogen starvation proteins, display an aberrant cell morphology under nitrogen-limiting conditions, and are impaired in the capacity to survive prolonged nitrogen starvation periods.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=101894Documentos Relacionados
- Pseudomonas putida KT2442 cultivated on glucose accumulates poly(3-hydroxyalkanoates) consisting of saturated and unsaturated monomers.
- m-Xylene-Responsive Pu-PnifH Hybrid σ54 Promoters That Overcome Physiological Control in Pseudomonas putida KT2442
- The nasB operon and nasA gene are required for nitrate/nitrite assimilation in Bacillus subtilis.
- gltB gene and regulation of nitrogen metabolism by glutamine synthetase in Escherichia coli.
- Structures of genes nasA and nasB, encoding assimilatory nitrate and nitrite reductases in Klebsiella pneumoniae M5al.