Properties of alpha-dehydrobiotin-resistant mutants of Escherichia coli K-12

We have isolated four classes of mutants resistant to alpha-dehydrobiotin, a biotin analogue. One mutant group, referred to as bioR shows high excretion levels of biotin vitamers, derepressed levels of the biotin biosynthetic enzymes, and resistance to repression by biotin. The mutation has been mapped between argC and bfe at min 79. A second class of mutants, with lesions in the bioA operon at min 17.5, shows derepressed levels of the dethiobiotin synthetase enzyme and has been tentatively designated as bioO mutants. The other two mutant groups show alterations in permeability: biotin uptake is markedly reduced in one, whereas in the other proline uptake is also affected. The former mutation lies near metE at min 75 and has been designated as bioP. The permeability mutants in the second group also show poor growth on minimal media, suggesting a generalized permeability effect. This mutation, designated as P, has not been mapped.