Molecular cloning, prokaryotic expression, purification, structural studies and functional implications of Heat Shock Protein 70 (Hsp70) from Rutilus frisii kutum

A novel Hsp70 chaperone from Rutilus frisii kutum was identified, cloned, expressed, purified and its functional characteristics revealed. The 3D structure of Hsp70 from Rutilus kutum was constructed using the crystal structure of E. coli Hsp70 as the template, with 47% sequence identity. The in vitro ATPase activity assay after 60 min, ATP hydrolysis of purified recombinant Hsp70 (8 μM) was improved by binding to denatured thermally luciferase (3 μM) about 2.5-fold compared with that of Hsp70 alone. Based on the results, it was found that the purified Hsp70 chaperone was able to considerably suppress heat-induced aggregation of luciferase by binding to DnaJ co-chaperone (5 μM) more than 70% after 10 min at 42 °C. In addition, Hsp70 DnaJ complex improved the refolding of heat-shocked luciferase nearly 40% after 60 min at 25 °C. It was concluded that Hsp70 protein from Rutilus frisii kutum has the critical role in preventing heat-induced aggregation of luciferase and refolding of heat-denatured luciferase was strictly dependent on the activity of Hsp70, thus, this protein can potentially be used for improving the functional properties of luciferase in various applications.