TABLE 1.

Escherichia coli strains and plasmids used in this study

Strain or plasmidGenotypeRelevant characteristic or deleted geneSource
Escherichia coli strains
    AG1recA1 endA1 gyrA96 thi-1 hsdR17 (rK mK+) supE44 relA1Cloning host strain22
    K-12 BW25113MG1655 F λ rrnB3 ΔlacZ4787 hsdR514 Δ(araBAD)567 Δ(rhaBAD)568 rph-1Wild type1
    JW0215K-12 BW25113 ΔyafQToxin, relBE family, inhibits translation through mRNA cleavage1
Plasmids
    pCA24N ptacpCA24N pT5-lac lacIq CmrHigh copy no., IPTG-inducible expression vector22
    pCA24N ptax::yafQpCA24N pT5-lac::yafQ lacIq CmrpCA24N containing the yafQ gene from E. coli K-1222