FIG. 8.

SL(dut) no. 5: inactivation of a chaperone/protease. (A) The position and orientation of the insert that caused synthetic lethality with dut is shown as a black flag above the genes pointing in the direction of its kanamycin gene. The small arrows on stems upstream of genes indicate promoters. (B) Spot test for synthetic lethality of ΔdegP dut mutants at 42°C and its suppression by inactivation of ung. Serial dilutions of rapidly growing cultures (10 μl) were spotted onto LB plates and incubated for 36 h at 28°C or for 16 h at 42°C. The dut recA(Ts) and dut recA(Ts) ung mutants were plated in parallel as controls. The strains were wild type, AB1157; dut, AK105; dut recA(Ts), AK106; dut recA(Ts) Δung, L-85; ΔdegP, HT81; ΔdegP dut, HT82; and ΔdegP dut Δung, HT83. (C) The explanation for the dut-1 degP synthetic lethality: aggravation through lack of support for the unstable mutant protein.