Figure 4: Inhibition of translation increases amplification and point mutation.
From: R-loops and nicks initiate DNA breakage and genome instability in non-growing Escherichia coli
Gene amplification (a) and point mutation (b) in WT (SMR4562) and mfd (PJH813) strains pulsed with spectinomycin (spec) (broken lines). WT+spec (
), WT (♦), mfd+spec (
), mfd (
). (c) The spectinomycin treatment-induced increase in point mutagenesis is DinB/Pol IV-dependent. Point mutation in WT (SMR4562) and dinB (SMR5830) cells pulsed with spec. WT+spec (), WT (♦), dinB+spec (), dinB (). The curves for the spectinomycin-treated WT cells differ from those of the untreated WT cells significantly, WT and spec-treated WT differ (for three experiments, P=0.002 for point mutation and 0.001 for amplification, Student’s t-test); mfd and spec-treated mfd are not significantly different (P=0.6 for point mutation, and 0.7 for amplification). (d) Spectinomycin treatment does not increase Lac+ revertants in cells overproducing RNase HI. Vector pBAD18 (), vector pBAD18 spec-treated (), pBAD18-rnhA (), pBAD18-rnhA spec-treated (); broken lines denote spectinomycin treatment. Error bars represent one s.e.m. of four parallel cultures. These experiments were performed three times with comparable results.
