DNA breaks-mediated cost reveals RNase HI as a new target for selectively eliminating antibiotic resistance

Roberto Balbontín; Nelson Frazão; Isabel Gordo

We show that mutations affecting transcription and translation generate DNA breaks, which explain 73% of the variation in their cost ( Figure 1 , Table 1 , Figure S1 ). Compensatory evolution indicates that these resistances cause uncoupling between transcription and translation (40) , which can result in DNA breaks (42). Indeed, we show that the RpsL K43N RpoB H526Y and RpsL K43T RpoB H526Y double mutants, which combine alleles that cause increased transcription elongation rate (12) and decreased translation rate (26, 69) , show the highest costs and DNA breaks ( Figure 1 ). Curiously, inhibition of translation has been shown to alleviate the cost of Rif R mutations in Pseudomonas aeruginosa (36) . In light of the results presented here, this observation is compatible with a scenario in which Rif R mutations cause a perturbation of transcription-translation coupling by virtue of reduced RNA polymerase processivity, and translation inhibitors promote re-coupling by decreasing ribosomal activity. In agreement with the notion of single resistance mutations causing significant uncoupling, single Rif R or Str R mutations with high cost (70) cause a strong induction of the SOS response ( Figure S7 ). We also showed that RNase HI is a key determinant of the fitness of resistant mutants ( Figure 4 , Table 1 , Figure S3 , Figure S4A , Figure S5 , Figure The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. . https://doi.org/10.1101/756767 doi: bioRxiv preprint