Figure 5.

Activation of CdiA-CT in E. coli cells results in growth arrest and tRNA degradation. (A) E. coli cysK⁺ ΔsspB cells producing the CdiA-CT/CdiI-DAS complex were treated with L-arabinose (L-ara) to induce synthesis of either SspB or SspB(Δ47) from plasmid vectors. Wild-type SspB delivers DAS-tagged CdiI immunity protein to the ClpXP protease, whereas the SspB(Δ47) variant does so less efficiently. Cell growth was monitored by measuring the OD₆₀₀ as a function of time. (B) Cells from the experiment in A were removed at various times, and total RNA was isolated for analysis by denaturing gel electrophoresis and Northern blot hybridization. The top panel shows total cellular RNA visualized by ethidium bromide staining. The bottom panels are Northern blots using probes specific for E. coli tRNA₂^Arg and tRNA₃^Gly. The gel migration positions of ribosomal RNAs (rRNAs) and tRNAs are indicated.