Fig. 5.

The holdase chaperone function of AtTDX enhances heat shock recovery in Arabidopsis. (A) Heat shock-dependent reversible changes of AtTDX oligomeric status in Arabidopsis suspension cells. Suspension cells cultured at 22 °C were heat-stressed at 40 °C for 10, 30, or 60 min. After 60 min of heat treatment (lane 4), the cells were transferred to their optimal temperature and incubated again for 3, 6, or 12 h. Cytosolic proteins were extracted from the treated cells and equal amounts (50 μg) were loaded onto the lanes of a native PAGE gel (Upper) and a reducing SDS/PAGE gel (Lower), followed by Western blot analysis with an anti-AtTDX-antibody. (B) (Upper) Expression levels of AtTDX in WT Arabidopsis and representative T₃ lines of transgenic Arabidopsis overexpressing AtTDX (OE), the AtTDX Cys-mutant (C304/307S), or the mutant suppressing the endogenous AtTDX protein (Sup) were analyzed by Western blotting on a SDS/PAGE gel. (Lower) Arabidopsis plants grown at 22 °C for 4 weeks are shown. (C) Comparison of heat shock tolerance between WT and transgenic Arabidopsis seedlings. (Upper) A scheme of heat shock treatment and recovery of the various Arabidopsis seedlings is depicted. (Lower) Comparison of plants on the final day of recovery after heat shock is shown.