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A single mutation leads to loss of glutamine synthetase and relief of ammonium repression inAspergillus

✍ Scribed by D. W. MacDonald

Book ID
104751948
Publisher
Springer-Verlag
Year
1982
Tongue
English
Weight
606 KB
Volume
6
Category
Article
ISSN
0172-8083

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✦ Synopsis

Glutamine synthetase activity in the ascomycete fungus Aspergillus nidulans is regulated by nitrogen source. The lowest activities are obtained when the fungus is grown on L-glutamine, and the highest activities when grown on L-glutamate + arabinose. Glutamine auxotrophs of the fungus have been isolated, and one of these mutant strains, glnA-1, has been shown to lack the enzyme glutamine synthetase. The mutation is recessive, and is located on the right arm of chromosome II. In addition to abolishing glutamine synthetase activity, the mutation results in the relief of repression for several enzyme activities normally subject to repression by ammonium. These include nitrate reductase, asparaginase, proline uptake and urea uptake.

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A nonsense mutation in the structural gene for glutamine synthetase leading to loss of nitrogen regulation in Klebsiella aerogenes
✍ Bender, Robert A. ;Eades, Linda J. πŸ“‚ Article πŸ“… 1982 πŸ› Springer 🌐 English βš– 530 KB

An amber mutation (glnA3711), the first nonsense mutation isolated in Klebsiella aerogenes, is described. When amber suppressors were present, the mutant made active glutamine synthetase which was more thermolabile than wild type, showing that glnA3711 lies in the structural gene for glutamine synth