Interaction of RNA polymerase mutations in haploid and merodiploid cells of Escherichia coli K-12.

Combination in the same chromosome of tsX mutation which affects the attachment of RNA polymerase to DNA template with either of two rifampicin resistant mutations (rif-r-1 or rif-r-5) is lethal. However tsX forms viable combination with other rifampicin resistant mutation—rif-r-76. Moreover a partial restoration of rifampicin binding capacity takes place: RNA polymerase from double tsX rif-r-76 mutant binds rifampicin better than the enzyme from tsX+ rif-r-76 cells. No mutual influence of rifampicin resistant and streptolydigin resistant mutations was found.