[Unusual structure of the regulatory region of the riboflavin biosynthesis operon in Bacillus subtilis].

Abstract

In vitro mutagenesis with methylhydroxylamine and nitrosomethylurea was used to obtain a number of Bacillus subtilis mutants impaired in flavin-dependent response. Mutants displayed varying degree of flavin-dependent repression of riboflavin synthase and of 6,7-dimethyl-8-ribityl-lumasine accumulation. Single nucleotide substitutions were detected by DNA sequencing in all of the mutants, affecting the 48 b.p. target area between the mRNA start and the AUG of the first gene.