FIGURE 6.

The Jd exerts a DnaK-dependent toxic effect on E. coli growth. Left, DnaJ, Jd(1–78), Jd(1–78) mutants and Jd(1–78)p5 were expressed from the l-arabinose-inducible vector pBAD22 in the Δ³ strain at 30 °C in the absence or presence of 1% l-arabinose. In the presence of l-arabinose, the expressed construct Jd(1–78) arrested cell growth. The Jd(1–78) was expressed from the l-arabinose inducible vector pBAD33 in the Δ⁴ strain at 30 °C in the absence or presence of 1% l-arabinose (ara). The empty vector pWSK29 or the vector pWSK29DnaK⁺ expressing DnaK under the control of its native promoter was also present. Jd(1–78) toxicity was relieved in the dnaK-null strain Δ⁴, but Jd(1–78) toxicity returned when DnaK was also co-expressed. Right, 15% SDS-PAGE showing that the lack of toxicity in Jd(1–78) is not due to a lower level of protein expression. Δ³ cells containing the empty vector pBAD22, Jd(1–78), or Jd(1–78)D35N were induced (I) with l-arabinose. After lysis of the cells, the proteins present in the soluble fractions were separated by SDS-PAGE. Uninduced (U) samples were also analyzed.