FIG. 8.

E. coli viability assay for GST-ς⁷⁰ mutants. Wild-type and mutant GST-ς⁷⁰ expression plasmids were transformed into MCS1 ptrp-rpoD cells (see Materials and Methods). After outgrowth, 4-μl aliquots of fourfold serial dilutions of each transformation were spotted onto L broth plates that contained ampicillin to select for the plasmid, either with or without 0.2 mM indole-3-acrylic acid (IAA) to induce ς⁷⁰ expression from the chromosomal ptrp-rpoD (provides wild-type ς⁷⁰).