An enzyme activity of Bacillus subtilis was found that catalyzes the dephosphorylation and deamination of phosphohomoserine to α ketobutyrate, resulting in a bypass of threonine in isoleucine biosynthesis. In crude extracts of a strain deficient in the biosynthetic isoleucine inhibitable threonine dehydratase, phosphohomoserine was converted to α ketobutyrate. Phosphohomoserine conversion to α ketobutyrate was shown not to involve a threonine intermediate. Single mutational events affecting threonine synthetase also affected the phosphohomoserine deaminating activity, suggesting that the deamination of phosphohomoserine was catalyzed by the threonine synthetase enzyme. It was demonstrated in vivo, in a strain deficient in the biosynthetic threonine dehydratase, that isoleucine was synthesized from homoserine without intermediate formation of threonine.
|Original language||English (US)|
|Number of pages||9|
|Journal||Journal of bacteriology|
|State||Published - Dec 1 1973|
ASJC Scopus subject areas
- Molecular Biology