Studies on the Biosynthesis of Aromatic Compounds in Neurospora crassa

Citation

Metzenberg, Robert Lee (1956) Studies on the Biosynthesis of Aromatic Compounds in Neurospora crassa. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/WPDV-8S11. https://resolver.caltech.edu/CaltechETD:etd-06102004-153533

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Mutant strains of Neurospora have been isolated which exhibit nutritional requirements for aromatic compounds. Some of these mutants require a single nutrient in order to grow, for example, tryptophan, phenylalanine, or tyrosine. Others have been found to require all three of these amino acids, and in addition, [...] acid. It was desired to ascertain the number of gene changes from wild type which are responsible for the observed nutritional requirements. For this purpose, a number of the new strains were subjected to genetic analysis. There was reason to believe that certain double and triple mutants would be found to accumulate compounds of interest which fail to accumulate in culture filtrates of strains containing only one altered gene. Therefore, these double and triple mutants were prepared by appropriate crosses, and were found to accumulate a number of compounds of biological interest. In addition, double and triple mutants have been of value in determining the order in which some of these genetic blocks occur in a biosynthetic sequence. Culture filtrates of the mutant strains have been examined for the presence of accumulated materials. Evidence is presented that the following compounds occur in filtrates of various mutants: protocatechuic acid, shikimic acid, 5-dehydroshikimic acid, vanillic acid, [...] acid, phenylpyruvic acid, anthranilic acid, prephenic acid, and [...]. Shikimic acid, although found to be accumulated in culture filtrates of one mutant, does not relieve the multiple requirement for aromatic compounds in other strains. This suggests that the biosynthesis of aromatic compounds in Neurospora may involve intermediates different from those elaborated by [...]. In the latter organism, 5-dehydroshikimic acid has been identified by Davis and co-workers as an "early" precursor of aromatic compound, whereas in Neurospora, it appears that 5-dehydroshikimic acid may be a "late" precursor, possibly the last compound that is a common precursor of all three aromatic amino acids. It was felt that a method for the detection of vicinal diol compounds on paper chromatograms would aid the identification of such compounds as shikimic acid in culture filtrates of the mutants. Therefore, a method based on periodate oxidation was developed and found to be of use in the detection of various compounds of biological importance.

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