The Arginine Regulatory Protein Mediates Repression by Arginine of the Operons Encoding Glutamate Synthase and Anabolic Glutamate Dehydrogenase in Pseudomonas aeruginosa
AUTOR(ES)
Hashim, Shehab
FONTE
American Society for Microbiology
RESUMO
The arginine regulatory protein of Pseudomonas aeruginosa, ArgR, is essential for induction of operons that encode enzymes of the arginine succinyltransferase (AST) pathway, which is the primary route for arginine utilization by this organism under aerobic conditions. ArgR also induces the operon that encodes a catabolic NAD+-dependent glutamate dehydrogenase (GDH), which converts l-glutamate, the product of the AST pathway, in α-ketoglutarate. The studies reported here show that ArgR also participates in the regulation of other enzymes of glutamate metabolism. Exogenous arginine repressed the specific activities of glutamate synthase (GltBD) and anabolic NADP-dependent GDH (GdhA) in cell extracts of strain PAO1, and this repression was abolished in an argR mutant. The promoter regions of the gltBD operon, which encodes GltBD, and the gdhA gene, which encodes GdhA, were identified by primer extension experiments. Measurements of β-galactosidase expression from gltB::lacZ and gdhA::lacZ translational fusions confirmed the role of ArgR in mediating arginine repression. Gel retardation assays demonstrated the binding of homogeneous ArgR to DNA fragments carrying the regulatory regions for the gltBD and gdhA genes. DNase I footprinting experiments showed that ArgR protects DNA sequences in the control regions for these genes that are homologous to the consensus sequence of the ArgR binding site. In silica analysis of genomic information for P. fluorescens, P. putida, and P. stutzeri suggests that the findings reported here regarding ArgR regulation of operons that encode enzymes of glutamate biosynthesis in P. aeruginosa likely apply to other pseudomonads.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=419967Documentos Relacionados
- Characterization and Regulation of the gbuA Gene, Encoding Guanidinobutyrase in the Arginine Dehydrogenase Pathway of Pseudomonas aeruginosa PAO1
- Crc Is Involved in Catabolite Repression Control of the bkd Operons of Pseudomonas putida and Pseudomonas aeruginosa
- Molecular Characterization and Regulation of an Operon Encoding a System for Transport of Arginine and Ornithine and the ArgR Regulatory Protein in Pseudomonas aeruginosa
- Purification and characterization of an arginine regulatory protein, ArgR, from Pseudomonas aeruginosa and its interactions with the control regions for the car, argF, and aru operons.
- Growth of Pseudomonas aeruginosa mutants lacking glutamate synthase activity.