title: Characterization of the glnK-amtB operon of Azotobacter vinelandii.
abstract: To determine whether in Azotobacter vinelandii the PII protein influences the regulation of nif gene expression in response to fluxes in the ammonium supply, the gene encoding PII was isolated and characterized. Its deduced translation product was highly similar to PII proteins from other organisms, with the greatest degree of relatedness being exhibited to the Escherichia coli glnK gene product. A gene designated amtB was found downstream of and was contranscribed with glnK as in E. coli. The AmtB protein is similar to functionally characterized ammonium transport proteins from a few other eukaryotes and one other prokaryote. glnK and amtB comprise an operon. Attempts to isolate a stable glnK mutant strain were unsuccessful, suggesting that glnK, like glnA, is an essential gene in A. vinelandii. amtB mutants were isolated, and although growth on limiting amounts of ammonium was similar in the mutant and wild-type strains, the mutants were unable to transport [14C]methylammonium.
authors.affiliation: Department of Plant Pathology, College of Agriculture, University of Arizona, Tucson 85721, USA.
authors.forename: D
authors.initials: D
authors.lastname: Meletzus
authors.forename: P
authors.initials: P
authors.lastname: Rudnick
authors.forename: N
authors.initials: N
authors.lastname: Doetsch
authors.forename: A
authors.initials: A
authors.lastname: Green
authors.forename: C
authors.initials: C
authors.lastname: Kennedy
mesh_terms: D016948:Azotobacter vinelandii / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001693:Biological Transport, Active / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D027682:Cation Transport Proteins; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D015870:Gene Expression; D005798:Genes, Bacterial; D008744:Methylamines / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009586:Nitrogen Fixation / Q000235:genetics; D009876:Operon; D051922:PII Nitrogen Regulatory Proteins
chemical_list: C111096:AmtB protein, E coli; D001426:Bacterial Proteins; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D008744:Methylamines; D051922:PII Nitrogen Regulatory Proteins; C404143:PIID regulatory protein, Bacteria; C027451:methylamine