yaaD and yaaE are involved in vitamin B6 biosynthesis in Bacillus subtilis

We show that yaaD and yaaE are involved in vitamin B6 (B6) biosynthesis in Bacillus subtilis. This is the first report which identifies genes involved in B(6) biosynthesis in B. subtilis. Based on homology, yaaD and yaaE belong to the highly conserved SNZ and SNO families, respectively. Disruptants of yaaD and yaaE required pyridoxal (PL) or pyridoxine (PN), and grew in the same way as the wild type in a minimal medium supplemented with 0.05 mM PL. The SNZ family is considered to be involved in singlet-oxygen resistance. Singlet-oxygen quenchers, L(+)-ascorbic acid and reduced glutathione, did not support the growth of these disruptants. Both yaaD and yaaE were transcribed at the highest level during the middle- to late-exponential phase and at a much lower level during the stationary phase. Neither PL nor PN affected the transcriptional rates of yaaD and yaaE. It is concluded that yaaD and yaaE are involved in B6 biosynthesis in B. subtilis, and are transcribed at the highest level during the middle- to late-exponential phase.