Allele-specific suppression of dnaA(Ts) mutations by rpoB mutations in Escherichia coli.

Extragenic suppressor mutations for dnaA (Ts) mutations mapping in the rpoB gene (beta-subunit of RNA polymerase) were isolated by selection of spontaneous rifampicin resistant mutants and screening for temperature resistance. Six rpoB mutations were analysed for suppression of 12 different dnaA (Ts) mutations. The analysis showed that all dnaA(Ts) mutations could be suppressed by some rpoB mutation. All six rpoB mutations showed allele specificity when tested for suppression of 12 dnaA(Ts) mutant strains. The allele specificity was found to correlate with the map position of the dnaA (Ts) alleles.