FIGURE 6.

IbOr holdase chaperone activity for IbPsbP. (A) IbOr regulates IbPsbP stability under heat stress in vitro. Equal amounts of purified IbPsbP were incubated at 50°C for 30 min, with or without IbOr. GST-IbPsbP fusion protein and His-IbOr fusion protein levels were detected by Coomassie brilliant blue staining of 12% SDS-PAGE gels (GST-IbPsbP, the second row; His-IbOr, the fourth row), followed by western blotting with the indicated antibodies (anti-GST, the first row; anti-His, the third row). Purified IbPsbP and IbOr proteins were loaded as controls. (B) IbOr regulates IbPsbP stability under heat stress in planta. Constructs containing indicated combinations were transiently overexpressed in 3-week-old N. benthamiana leaves by Agrobacterium infiltration. Heat stress (in 38°C for 1 h) were treated at 3 days after infiltration. Total proteins were extracted from infected leaves and followed by western blotting with the indicated antibodies (anti-GFP, the first row; anti-FLAG, the second row; anti-GUS, the third row). GUS protein were used as expression control.