title: Role of glutamine synthetase in phenazine antibiotic production by Pantoea agglomerans Eh1087.
abstract: Pantoea agglomerans strain Eh1087 produces the phenazine antibiotic D-alanylgriseoluteic acid. A glutamine auxotroph harboring an insertion in a putative glnA gene was obtained by transposon-mutagenesis of Eh1087 that produced less D-alanylgriseoluteic acid than the parental strain (strain Eh7.1). Cosmids encoding the Eh1087 glnA were isolated by their ability to complement the mutant for prototrophy. The role of the Eh1087 glnA locus was functionally confirmed by complementation of an Escherichia coli glnA mutant. Analysis of the nucleotide and deduced amino acid sequences of the Eh1087 glnA gene indicated a high degree of similarity to the glnA genes and glutamine synthetase enzymes of other Enterobacteriaceae. Isotopic labelling experiments with 15N-labelled ammonium sulfate demonstrated that wild-type Eh1087 incorporated 15N into griseoluteic acid more readily than the glnA mutant Eh7.1. We conclude that the 2 nitrogens in the phenazine nucleus originate from glutamine and the intracellular glutamine synthesized by Eh1087 is a source of the phenazine nucleus nitrogens even in glutamine-rich environments.
authors.affiliation: School of Biological Sciences, University of Canterbury, Christchurch, New Zealand.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Galbraith
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Giddens
authors.forename: H Khris
authors.initials: HK
authors.lastname: Mahanty
authors.forename: Bruce
authors.initials: B
authors.lastname: Clark
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D005974:Glutamate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D020636:Pantoea / Q000201:enzymology* / Q000235:genetics; D010619:Phenazines / Q000378:metabolism*; D017422:Sequence Analysis, DNA
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D010619:Phenazines; D005973:Glutamine; D005974:Glutamate-Ammonia Ligase