Fig. 6

Farnesylated AtJ3 produced in E. coli prevents plant-synthesized luciferase from heat-induced denaturation. a The luminescence was observed in Pro_LeHsp23.8-Fluc/j3 after a 2 h incubation at 37 °C, indicating the induction of luciferase. b Cell lysate from 2 h heat-incubated Pro_LeHsp23.8-Fluc/j3 plants was mixed with proteins extracted from E. coli cells harboring both pGEX-AtJ3 and pRSF-Duet1-AtPFT (containing GST-tagged farnesylated AtJ3; GST-farnesylated J3), pGEX-AtJ3 alone (containing GST-tagged unfarnesylated AtJ3; GST-J3) and pGEX-4T-1 empty vector and pRSF-Duet1-AtPFT (containing GST). The mixtures were then incubated at 44 °C for different durations (0, 3, and 5 min), and the intensity of luciferase activities was monitored by measuring the luminescence. Results showed that after 3 min of heat stress, the mixture with farnesylated AtJ3 maintained a significantly higher luminescent signal (85.9%) than those with unfarnesylated AtJ3 (58.0%) or no AtJ3 (63.9%), indicating that the farnesylated AtJ3 produced in E.coli retained its ability to protect plant-synthesized proteins from thermal denaturation. Values represent the mean ± SD of three biological replicates. *P ≤ 0.01 (unpaired t-test)