In vivo roles of Bm3R1 repressor in the barbiturate-mediated induction of the cytochrome P450 genes (P450(BM-3) and P450(BM-)1) of Bacillus megaterium.
We previously showed [Q. Liang, A.J. Fulco, J. Biol. Chem., 270 (1995) 18606-18614) that the binding of Bm3R1 repressor to Barbie box elements and operator sites in the 5'-flanking regions of the P450BM-3 and P450BM-1 (CYP102 and CYP106) genes in Bacillus megaterium was a critical factor in their regulation at the level of transcription. We now describe experiments that delineate specific roles for Bm3R1 in the barbiturate-mediated induction of these genes. We directly demonstrate the interaction of Bm3R1 with Barbie box and operator sequences and show that high in vivo levels of Bm3R1 prevent putative positive factors from binding to Barbie box elements, strongly inhibit the expression of the P450 genes, prolong the lag phase of growth in Bacillus megaterium cultures and increase the sensitivity of the cells to the growth-inhibitory effects of barbiturates. Finally, our data suggest that there may be two forms of Bm3R1, either of which can interact with OIII, the bicistronic operator sequence.
Liang
Q
Q
Department of Biological Chemistry, School of Medicine, University of California, 4042A Young Hall, 607 Circle Drive South, Los Angeles, CA 90095-1569, USA.
Chen
L
L
Fulco
A J
AJ
D001410:Bacillus megaterium / Q000201:enzymology / Q000235:genetics*; D001426:Bacterial Proteins / Q000378:metabolism / Q000502:physiology*; D001463:Barbiturates / Q000494:pharmacology*; D001665:Binding Sites; D001667:Binding, Competitive; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D015870:Gene Expression / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics*; D017930:Genes, Reporter / Q000235:genetics; D006899:Mixed Function Oxygenases / Q000235:genetics; D009251:NADPH-Ferrihemoprotein Reductase; D009875:Operator Regions, Genetic; D011485:Protein Binding / Q000502:physiology; D012097:Repressor Proteins / Q000502:physiology*; D012680:Sensitivity and Specificity; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000235:genetics
D001426:Bacterial Proteins; D001463:Barbiturates; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C073493:Bm3R1 protein, Bacillus megaterium; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D009251:NADPH-Ferrihemoprotein Reductase; C052423:flavocytochrome P450 BM3 monoxygenases; D015500:Chloramphenicol O-Acetyltransferase