GROWTH-RESPONSE TO 4-HYDROXY-L-THREONINE OF ESCHERICHIA-COLI MUTANTS BLOCKED IN VITAMIN-B6 BIOSYNTHESIS

Mutants of Escherichia coli (pdx B and pdx C) which are blocked in the biosynthesis of pyridoxol (vitamin B-6) showed a growth response to 4-hydroXy-L-threonine. This observation constitutes the first direct evidence in support of the view that 4-hydroxy-L-threonine is implicated in the biosynthesis of vitamin B-6. 1-Aminopropan-2,3-diol, the decarboxylation product of 4-hydroxy-L-threonine, does not support the growth of these mutants. Deuterium from deuterium-labelled I-aminopropan-2,3-diol was not incorporated into pyridoxol.