FIGURE 7.

Compensation of Jd toxicity by co-expression of GrpE or lidless DnaK(1–517). a, DnaJ, Jd(1–78), and Jd(1–78)D35N were expressed from the l-arabinose-inducible vector pBAD33 in the Δ³ strain at 30 °C in the absence or presence of 1% l-arabinose (ara). GrpE was simultaneously expressed from the IPTG-inducible vector pSE380 with 0.05 mm IPTG. Overexpression of GrpE also compensated for the toxicity conferred by Jd(1–78) (compare dilutions labeled Jd(1–78)+vector and Jd(1–78)+GrpE for growth in the presence of arabinose and IPTG). b, 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. The empty vector pWSK29, the vector pWSK29DnaK⁺ containing DnaK under its native promoter, or the vector pWSKLidless containing lidless DnaK(1–517) also under the DnaK native promoter were present. When lidless DnaK(1–517) was expressed in the place of DnaK, overexpression of Jd(1–78) did not result in any toxicity (compare dilutions labeled Jd(1–78)+DnaK and Jd(1–78)+Lidless for growth in the presence of arabinose). c, 15% SDS-PAGE showing lack of toxicity upon co-overexpression of lidless DnaK(1–517) is not due to a poor expression level of the protein. Δ⁴ cells containing the empty vector pSE380, DnaK, or lidless DnaK(1–517) were induced (I) with IPTG. After lysis of the cells, the proteins present in the soluble fractions were separated by SDS-PAGE. Uninduced (U) samples were also analyzed.