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. Author manuscript; available in PMC: 2010 Jun 7.
Published in final edited form as: Mol Cell. 2007 Apr 27;26(2):273–286. doi: 10.1016/j.molcel.2007.03.012

Figure 1.

Figure 1

RecA-, RecF-, and RecQ-Mediated Inviability of Δruv ΔuvrD Cells

(A) Phage P1 co-transduction assay for synthetic lethality. Transducing DNA fragments from phage grown on a donor strain marked with Tet near a mutation of interest (Δruv::Kan) are used to transduce “wild-type” and isogenic mutant recipients. The frequency of co-transduction of Δruv::Kan with Tet depends on the distance between the two markers. E.g., when there is 75% linkage, the two markers are co-transduced in 75% of Tet-resistant (TetR) transductants. Recipient mutants inviable in combination with Δruv fail to produce colonies that carry both Tet marker and the linked Δruv::Kan, thereby reducing the co-transductant frequency.

(B–O) Co-transduction data. Means ± SEM, n ≥ 3 independent determinations each. WT, wild-type. Inefficient recovery of (B) ΔruvB::Kan zea-3::Tn10, (D) ΔruvA::Kan eda-51::Tn10, or (E) ΔruvC::Kan eda-51::Tn10 co-transductants of ΔuvrD, rescued by ΔrecQ (Tn10 carries the Tet element). (C) ΔuvrD does not alter linkage/co-transductant frequencies generally (black bars, donor has Zeo marker near ruv+), but is specific to transduction of ruv mutations into ΔuvrD strains (gray bars, donor: ΔruvB::Kan zea-3::Tn10). (F) Neither MMR nor NER defects cause inviability with ΔruvB. (G) Loss of HR at the strand-exchange stage (ΔrecA) is viable with ΔuvrD. (H) ΔrecB is viable with ΔuvrD. (I) Loss of RecA rescues the ΔruvB ΔuvrD inviability. (J) ΔrecF rescues the ΔruvB ΔuvrD inviability. (K) Loss of RecB does not rescue ΔruvB ΔuvrD inviability. (L) Loss of SulA does not rescue ΔruvB ΔuvrD inviability. (M) RecQ promotes death of recombination-proficient/SOS-deficient cells. SOS-deficient [lexA3(Ind−)] ΔruvB ΔuvrD cells are dead when RecA levels are not limiting due to a recA operator-constitutive allele, recAo281 [gray bars, recAo281 lexA3(Ind−) ΔruvB compared with lexA3(Ind−) ΔruvB and ΔruvB]. ΔrecQ rescues recAo281 lexA3(Ind−) ΔruvB ΔuvrD inviability (black bars; P1 donor also contains ΔrecQ, which cotransduces normally with ΔuvrD. See Supplemental Data.). (N) Loss of RecX does not rescue ΔruvB ΔuvrD inviability. (O) ΔrecJ rescues the ΔruvB ΔuvrD inviability.