The arcABDC gene cluster, encoding the arginine deiminase pathway of Bacillus licheniformis, and its activation by the arginine repressor ArgR

The arginine deiminase pathway enables Bacillus licheniformis to grow anaer obically on arginine, Both the presence of arginine and anaerobiosis are ne eded to trigger induction of the pathway. In this study we have cloned and sequenced the are genes encoding the pathway. They appear clustered in an o peron-like structure in the order arcA (arginine deiminase), arcB (ornithin e carbamoyltransferase), arcD (putative arginine-ornithine antiporter), arc C (carbamate kinase). It was found that B. licheniformis has an arginine re pressor, ArgR, homologous to the B. subtilis arginine repressor AhrC, Mutan ts affected in argR were isolated. These mutants have lost both repression by arginine of the anabolic ornithine carbamoyltransferase and induction of the arginine deiminase pathway. Electrophoretic band shift experiments and DNase I footprinting revealed that in the presence of arginine, ArgR binds to a site upstream from the are promoter. The binding site is centered 108 nucleotides upstream from the transcription start point and contains a sin gle Arg box.