Pleiotropic, extragenic suppression of dna mutants in Bacillus subtilis

Thermosensitive (dna) mutants of Bacillus subtilis defective in deoxyribonucleic acid replication can be divided into two groups on the basis of their ability to spontaneously yield secondary mutants with an HDS phenotype (thermoin-sensitivity and resistance to aryl-azo-pyrimidines) at frequencies higher than 10(-8). Such a phenotype is due to alleles at the hds locus (mapping close to cysA), which act as extragenic pleiotropic suppressors. HDS suppressibility has been used as a screening tool to identify new dna strains among uncharacterized temperature-sensitive mutants.