Rhodopseudomonas palustris, Glutamine Synthetase, Dye-Ligand Chromatography, Nitrogen Fixation, Ammonium Assimilation The phototrophic bacterium Rhodopseudomonas palustris assimilated ammonium via glutamine synthetase and glutamate synthase. Diazotrophic and ammonium-grown cells had high levels of both enzymes, whereas enzymes of alternative assimilatory pathways were absent or had only low act...

Saccharomyces cerevisiae glutaminyl-tRNA synthetase mutants were isolated through systematic screening of tight Glnderivatives of a leaky glutamine auxotroph. These mutations define a single nuclear gene, GLN4. The gln4-1 mutation is specific for Gln-tRNA synthetase and shows a dosage effect in heterozygous diploids. The wild-type Gln-tRNA synthetase exhibits a Km for glutamine of 25 ,uM; the g...

The PII protein is Escherichia coli's cognate transducer of the nitrogen signal to the NRII (NtrB)/NRI (NtrC) two-component system and to adenylyltransferase. Through these two routes, PII regulates both amount and activity of glutamine synthetase. GlnK is the recently discovered paralogue of PII, with a similar trimeric x-ray structure. Here we show that PII and GlnK form heterotrimers, in E. ...

The book is well produced by photo-offset reproduction from typescript and contains a large number of figures, illustrations and diagrams. There is a comprehensive collection of references which is complete until 1972. The work is divided into two parts, the first dealing with enzymes involved in glutamats-glutamine interconversion and the second discussing those enzymes that use the amide nitr...

Glutamine-dependent carbamyl phosphate synthetase (from Escherichia coli) was previously shown to be composed of a light subunit (molecular weight similar to 42,000) which has the binding site for glutamine and a heavy subunit (molecular weight similar to 130,000) which has binding sites for the other reactants and allosteric effectors. The subunits may be separated with retention of catalytic ...

The first step in the proteolytic degradation of bacterial glutamine synthetase is a mixed function oxidation of one of the 16 histidine residues in the glutamine synthetase subunit (Levine, R. L. (1983) J. Biol. Chem. 258, 11823-11827). A model system, consisting of oxygen, a metal ion, and ascorbic acid, mimics the bacterial system in mediating the oxidative modification of glutamine syntheta...

The behavior of phosphoribosylformylglycinamidine (FGAM) synthetase (EC 6.3.5.3) activity was elucidated in normal and proliferating tissues and in murine and human neoplasms. Enzymic activity was measured in the 100,000 x g crude super natant fluid prepared from tissue homogenates. The assay was based on coupling FGAM produced to diazotizable aminoimidazole ribonucleotide. In the crude extract...

Glutamine synthetase is a key enzyme which has a regulatory role in the brain glutamate pool. According to previously published proteomic analysis, it was shown that the expression level of this enzyme is affected by morphine administration. In our study, we examined the activity of glutamine synthetase in various structures of rat brain (cortex, striatum, hippocampus and spinal cord) that are ...

Under certain conditions of growth, the Escherichiu coli glutamine synthetase is modified by the introduction into the enzyme molecule of covalently bound adenylic acid. This mechanism for modification of the preformed enzyme was discovered independently in this country by Kingdon and Stadtman (1, 2) and in Germany by Holzer et al. (3, 4). An enzyme was described by Kingdon, Shapiro, and Stadtm...

The cortisol induction of the enzyme glutamine synthetase (EC 6.4.1.2) in the embryonic chick neural retina is controlled initially at the transcriptional level, as previously demonstrated by the unique appearance of a 15 S RNA species which codes for a single and identical polypeptide chain of glutamine synthetase. This is found only on polyribosomes of cortisol-treated retinas. Recent experim...