Genetic and biochemical characterization of kirromycin resistance mutations in Bacillus subtilis

Abstract

Spontaneous mutations causing resistance to the EF[elongation factor]-Tu-specific antibiotic kirromycin were isolated and mapped in B. subtilis. Three-factor transductional and transformational crosses have placed the kir locus proximal to ery-1 and distal to strA (rpsL) and several mutations affecting EF-G and EF-Tu, in the order: .**GRAPHIC**. Purified EF-Tu from mutant strains is more resistant to kirromycin as measured by in vitro protein synthesis and also shows a more acidic isoelectric point than wild-type EF-Tu. This indicates that the kir locus is the genetic determinant (tuf) for EF-Tu and that there is a single active gene for this enzyme in B. subtilis.