THERMOSENSITIVE PDXJ MUTATION AFFECTING VITAMIN-B6 BIOSYNTHESIS IN ESCHERICHIA-COLI K-12

A temperature-sensitive mutation affecting pyridoxine biosynthesis in Escherichia coli has been isolated following nitrosoguanidine mutagenesis. This is the first report of a conditional mutation affecting that pathway. Three-point transductional analysis and an Hfr mating test indicate that the affected locus is pdxJ and that the gene order is glyA-purI-pdxJ-nadB. The data confirm the present genetic map position of pdxJ, which had not been accurately determined. Cells carrying the mutation exhibit an absolute requirement for 2.5 μM vitamin B6 when inenbated at temperatures of 38°C or higher. © 1979 Springer-Verlag New York Inc.