EVIDENCE AGAINST THE BM1P1 PROTEIN AS A POSITIVE TRANSCRIPTION FACTORFOR BARBITURATE-MEDIATED INDUCTION OF CYTOCHROME P450(BM-1) IN BACILLUS-MEGATERIUM

The Bm1P1 protein was previously proposed to act as a positive transcr iption factor involved in barbiturate-mediated induction of cytochrome P450(BM-1) in Bacillus megaterium. We now report that the bm1P1 gene encodes a protein of 217 amino acids, rather than the 98 amino acids a s reported previously. In vitro gel shift assays indicate that the Bm1 P1 protein did not interact with probes comprising the regulatory regi ons of the P450(BM-1) gene. Moreover, disruption of the bm1P1 gene did not markedly affect barbiturate induction of P450(BM-1) expression. A multicopy plasmid harboring only the P450(BM-1) promoter region could increase expression of the chromosome-encoded P450BM-1. The level of expression is comparable with that shown by a multicopy plasmid harbor ing the P450(BM-1) promoter region along with the bm1P1 gene. These re sults strongly suggest that the Bm1P1 protein is unlikely to act as a positive regulator for barbiturate induction of P450(BM-1) expression. Finally, deletion of the Barbie box did not markedly diminish the eff ect of pentobarbital on expression of a reporter gene transcriptionall y fused to the P450(BM-1) promoter. This suggests that the Barbie box is unlikely to be a key element in barbiturate-mediated induction of P 450(BM-1).