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When cultured tobacco cells are provided growth-limiting concentrations of sulfur as sulfate, the rate of development of nitrate reductase (NADH:nitrate oxidoreductase, EC is proportional to the initial sulfate concentration. When the cells are provided growth-limiting concentrations of nitrogen as nitrate, the rate of derepression of ATP(More)
The ATP sulfurylase of cultured tobacco cells is repressed during growth on readily assimiliated sulfur sources, such as sulfate, L-cysteine, or L-methionine, but it is derepressed during growth on slowly assimiliated sulfur sources, such as L-djenkolate or glutathione, or during sulfur starvation. The enzyme is not induced by sulfate. The enzyme level in(More)
Certain mutations at the glaB locus result in the failure to fully derepress glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC] and to convert it to the active nonadenylylated form in response to nitrogen limitation. In these mutants the PII regulatory protein is altered such that it cannot be converted by uridylyltransferase to the(More)
Six independent secretion-defective mutations were found that result in failure to release protein from the membrane into the periplasmic space of Salmonella typhimurium after removal of the signal peptide. The mutant protein is found in a membrane-bound form accessible to trypsin added to intact spheroplasts. The phenotype of these mutations supports the(More)
  • Z Reuveny
  • Proceedings of the National Academy of Sciences…
  • 1977
Molybdate and selenate are structural analogs of sulfate that inhibit synthesis of adenosine 5'-phosphosulfate by ATP sulfurylase (sulfate adenylyltransferase, ATP:sulfate adenylyltransferase, EC in crude extracts of tobacco XD cells. Both of these anions derepress ATP sulfurylase in cells growing on sulfate, but not in cells growing on L-cysteine.(More)
A mutation of Klebsiella aerogenes causing production of an altered PII regulatory protein which stimulates overadenylylation of glutamine synthetase and also prevents its derepression was combined with mutations abolishing the activity of adenylyltransferase. The results support the idea that PII plays a role in the regulation of the level of glutamine(More)
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