In Vivo Resolution of Conflicting In Vitro Results: Synthesis of Biotin from Dethiobiotin Does Not Require Pyridoxal Phosphate

The source of the biotin sulfur atom remains a contested point in studies of biotin synthase (BioB) in vitro. Recent reports that BioB has an intrinsic pyridoxal phosphate (PLP)-dependent cysteine desulfurase activity were tested by depleting Escherichia coli cells of PLP. The BioB-dependent conversion of dethiobiotin to biotin proceeded in these cells irrespective of the presence or absence of PLP.