Relationship of Glutaric Acid to the Homocitric Acid Pathway of Biosynthesis of Lysine in Yeast
1969; Elsevier BV; Volume: 244; Issue: 6 Linguagem: Inglês
10.1016/s0021-9258(18)91777-1
ISSN1083-351X
AutoresJ. K. Bhattacharjee, Anthony F. Tucci,
Tópico(s)Fungal and yeast genetics research
ResumoAbstract Several approaches have been used to elucidate the relationship of glutaric acid to the pathway for the biosynthesis of lysine in yeast. A comparative study of several auxotrophic mutants reveals that α-ketoadipate and glutarate are accumulated only in certain mutants that fail to utilize α-aminoadipic acid, a precursor of lysine, for growth. Neither wild type culture nor mutants that are blocked at intermediary steps leading to α-ketoadipate formation accumulate α-ketoadipate or glutarate. A yeast cell-free preparation decarboxylates α-ketoadipate and the activity is not dependent on oxygen. The α-ketoadipate decarboxylation is similar to α-carboxylase activity of yeast. The product of such a decarboxylation yields a 2,4-dinitrophenylhydrazone derivative that shows similar chromatographic mobility to the 2,4-dinitrophenylhydrazone of synthetic glutaric semialdehyde. Cell-free preparations from mutant 1y5, which accumulates glutarate and α-ketoadipate, do not show significantly higher decarboxylase activity than wild type yeast with α-ketoadipate as a substrate. Of the radioactivity incorporated into cell protein, the percentage going to lysine is not significantly different when 1,5-14C-glutarate or 2-14C-acetate is used as precursor. These precursors are much less selective for lysine (l10%) than 6-14C-dl-α-aminoadipic acid (g90%) in growing yeast culture. These results indicate that glutaric acid is not an obligatory intermediate of the homocitric acid pathway.
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