title: Purification and properties of glutamine synthetase from Hydrogenobacter thermophilus TK-6.
abstract: Hydrogenobacter thermophilus TK-6, a thermophilic and obligately chemoautotrophic bacterium, assimilates ammonium using glutamine synthetase (GS). GS was purified using three chromatography steps. The purified GS was found to belong to GS type I on the basis of its subunit composition and molecular weight. The Mg2+ -dependent activity of this GS significantly increased after incubation with phosphodiesterase, indicating that GS is subject to adenylyl/deadenylyl regulation, a posttranslational modification system reported mainly among enterobacteria. The degree of this posttranslational modification changed depending on growth phase, confirming that adenylyl/deadenylyl regulation functions in vivo. Interestingly, the Km for glutamate of H. thermophilus GS was significantly higher than those of other organisms, suggesting that GS activity is affected by intracellular glutamate concentration.
authors.affiliation: Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kameya
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Arai
authors.forename: Masaharu
authors.initials: M
authors.lastname: Ishii
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Igarashi
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification*; D004789:Enzyme Activation; D004795:Enzyme Stability; D005974:Glutamate-Ammonia Ligase / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D001426:Bacterial Proteins; D005974:Glutamate-Ammonia Ligase