Lysine Metabolism in Neurospora

Citation

Good, Norman Everett (1952) Lysine Metabolism in Neurospora. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/T8E4-N918. https://resolver.caltech.edu/CaltechTHESIS:10062017-091942585

Abstract

The lysine requiring mutants of Neurospora crass, when classified by the criteria of symbiotic, specificity of growth requirements, intersterility and genetic recombination, fall into five groups representing at least five loci. Members of two groups are capable of growth on a minimal medium supplemented with either lysine, ∈-hydroxynorleucine or α-aminoadipic acid. Members of a third group can utilize lysine or ∈-hydroxynorleucine, while members of the fourth and fifth group are unable to grow in the absence of lysine itself.

The D-isomers of all these amino acids stimulate growth in the presence of the natural isomers. Nevertheless their α-keto analogues when added to the medium are without effect. Since it has been shown that Neurospora has enzymes cata­lyzing the interconversions of α-aminoadipic and α-keto­-adipic acids, the nonutilization of the exogenous keto acids is ascribed to a failure of assimilatory mechanisms.

Investigations of the incorporation of isotopic nitrogen into the mycelial lysine indicate that both the α and ∈-amino groups are quite stable. Inasmuch as the nitrogen of α-aminoadipic acid is labile it is suggested that the de­gradation of lysine via that acid is not quantitatively sig­nificant.

None of a number of other substances which might be postulated either as precursors of α-aminoadipic acid or as intermediates between that acid and lysine has any effect on growth. Syntheses of several of these compounds are described.

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