Bacillus subtilis 168 Mutants Resistant to Arginine Hydroxamate in the Presence of Ornithine or Citrulline

Publisher Website
Google Scholar
Abstract
Mutations in B. subtilis 168 were isolated that confer resistance to arginine hydroxamate in the presence, but not absence, of ornithine. Seven such Ahor mutants were studied in detail. In common with certain classes of Ahr mutant (resistant to arginine hydroxamate in the absence of arginine precursors) described previously, these Ahor mutants showed little or no inducibility of enzymes of arginine catabolism. Mutants that showed no inducibility were unable to utilize arginine or ornithine as sole N source. The only biosynthetic enzyme to show any consistent differences in activity from the parent was ornithine carbamoyltransferase, whose level was slightly elevated in cells grown in the presence of ornithine or citrulline. Phage PBS1 transduction crosses showed that 2 of the ahor mutations map at the ahrA locus, while a third (unique in its resistance to arginine hydroxamate in the presence of citrulline) mapped at a hitherto undescribed locus closely linked to metC, designated ahrD.