Some E. coli genes encoding proteins synthesized after MazF induction are involved in cell death, and some in cell survival.

(A) Identified proteins (circled), which are synthesized after MazF induction. (B) Genes encoding the proteins identified in (A) were individually deleted from the chromosome of E. coli MC4100 relA+. These deletion mutants, as well as the WT and its ΔmazEF derivative as controls, were briefly treated with spectinomycin to inhibit translation for only a short period, and then plated to determine viability (Materials and Methods). (C) As In (B), but the cells were treated with nalidixic acid to cause damage to the DNA. Genes whose deletion resulted in increased viability were called “Death Genes”. Genes whose deletion resulted in reduced viability were called “Survival Genes.”