Alternate Pathway for Isoleucine Biosynthesis in Escherichia coli
AUTOR(ES)
Phillips, A. T.
RESUMO
A threonine dehydrataseless mutant of Escherichia coli, Crookes strain, was observed to grow on an acetate minimal medium without the usual requirement for isoleucine supplementation. Both the wild-type Crookes strain and a threonine auxotroph metabolized l-glutamate-1-14C to l-isoleucine-1-14C with no appreciable randomization, suggesting that a pathway for isoleucine formation from glutamate via β-methylaspartate, β-methyloxaloacetate, and α-ketobutyrate was possible in addition to the pathway from threonine and α-ketobutyrate. Crude cell-free extracts formed 14C-β-methylaspartate from 14C-glutamate, and the conversion of β-methylaspartate to α-ketobutyrate was also demonstrated, thus supporting the conclusion that glutamate can serve as a precursor of α-ketobutyrate (and isoleucine) without the necessary involvement of threonine as an intermediate.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=285197Documentos Relacionados
- Genetic characterization of a highly efficient alternate pathway of serine biosynthesis in Escherichia coli.
- Inhibition of Escherichia coli isoleucine biosynthesis by isoleucine tetrazole.
- Direct homocysteine biosynthesis from O-succinylhomoserine in Escherichia coli: an alternate pathway that bypasses cystathionine.
- Isoleucine and Valine Metabolism in Escherichia coli XIX. Inhibition of Isoleucine Biosynthesis by Glycyl-Leucine
- Amino Acid Biosynthesis in the Spirochete Leptospira: Evidence for a Novel Pathway of Isoleucine Biosynthesis