Acetylhomoserine and Methionine Biosynthesis in Neurospora
1966; Elsevier BV; Volume: 241; Issue: 16 Linguagem: Inglês
10.1016/s0021-9258(18)99850-9
ISSN1083-351X
Autores Tópico(s)Metabolism and Genetic Disorders
ResumoAbstract This communication reports several independent observations which suggest that O-acetylhomoserine is an intermediate in methionine biosynthesis in Neurospora. Indirect evidence has long implicated three unlinked genes (me-3, me-5, me-7) in a hypothetical series of reactions leading to the formation of cystathionine from homoserine and cysteine in Neurospora, but the metabolic defects associated with mutations in these genes have not been ascertained. It has now been shown that me-5 mutants, but not me-3 or me-7, will grow in the presence of O-acetylhomoserine. Second, when grown in the presence of methionine and labeled homoserine, me-5 mutants fail to accumulate two compounds which are formed by me-3, me-7, and wild type: O-acetylhomoserine, and a larger amount of 4-O-acetyl-2,4-dihydroxybutyrate. Third, me-5 mutants lack an enzyme catalyzing an exchange between labeled homoserine and O-acetylhomoserine.
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