Regulation of anaerobic arginine catabolism in Bacillus licheniformis by aprotein of the Crp/Fnr family

Arginine anaerobic catabolism occurs in Bacillus licheniformis through the arginine deiminase pathway, encoded by the gene cluster arcABDC. We report here the involvement of a new protein, ArcR, in the regulation of the pathw ay. ArcR is a protein of the Crp/Fnr family encoded by a gene located 109 b p downstream from arcC. It binds to a palindromic sequence, very similar to an Escherichia coli Crp binding site, located upstream from arcA. Residues in the C-terminal domain of Crp that form the DNA binding motif, in partic ular residues Arg-180 and Glu-181 that make specific bonds with DNA, are co nserved in ArcR, suggesting that the complexes formed with DNA by Crp and A rcR are similar. Moreover, the pattern of DNase I hypersensitivity sites in duced by the binding of ArcR suggests that ArcR bends the DNA in the same w ay as Crp. From the absence of anaerobic induction following inactivation o f arcR and from the existence of a binding site upstream of the arcA transc ription start point, it can be inferred that ArcR is an activator of the ar ginine deiminase pathway. (C) 2000 Federation of European Microbiological S ocieties. Published by Elsevier Science B.V. All rights reserved.