title: Characterization of two glutaminases from the filamentous cyanobacterium Anabaena sp. PCC 7120.
abstract: The Anabaena genome contains two ORFs that appear to encode glutaminases. The genes were expressed as histidine-tagged fusion proteins in Escherichia coli. The purified proteins possessed glutaminase activity using l-glutamine as the substrate, but differed in biochemical properties. All2934 showed an optimal activity at 20 degrees C and pH 6.0, with a higher affinity for l-glutamine than All4774, which had optimal activity at 37 degrees C and pH 7.5. Remarkably, the glutaminase activity of All2934 was phosphate dependent, while All4774 was phosphate independent. The expression of all2934 and all4774 was analyzed using semi-quantitative reverse transcriptase-PCR. The expression level of all2934 was much higher than that of all4774 under normal and nitrogen-depletion conditions, indicating that All2934 may play an important role in metabolizing glutamine in Anabaena.
authors.affiliation: Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
authors.forename: Jun Xia
authors.initials: JX
authors.lastname: Zhou
authors.forename: Jie
authors.initials: J
authors.lastname: Zhou
authors.forename: Hao Meng
authors.initials: HM
authors.lastname: Yang
authors.forename: Mei
authors.initials: M
authors.lastname: Chen
authors.forename: Fang
authors.initials: F
authors.lastname: Huang
mesh_terms: D000595:Amino Acid Sequence; D017033:Anabaena / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005972:Glutaminase / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins; D005972:Glutaminase; D009584:Nitrogen