دانلود رایگان مقاله نظارت بی درنگ آرتمین در فعالیت نگهبانی درون جانداری با لوسیفراز

Abstract

Artemin is an abundant thermostable protein in Artemia encysted embryos and considered as a stress protein, as its highly regulated expression is associated with stress resistance. Artemin cDNA was previously isolated and cloned from Artemia urmiana and artemin was found as an efficient molecular chaperone in vitro. Here, co-transformation of E. coli was performed with two expression vectors containing artemin and firefly luciferase for in vivo studies. The time-course of luciferase inactivation at low and elevated temperatures showed that luciferase was rapidly inactivated in control cells, but it was found that luciferase was protected significantly in artemin expressing cells. More interestingly, luciferase activity was completely regained in heat treated artemin expressing cells at room temperature. In addition, in both stress conditions, similar to residual activity of luciferase, cell viability in induced cultures over-expressing artemin was significantly higher than non-expressed artemin cells. It can be suggested that artemin confers impressive resistance in stressful conditions when introduced into E. coli cells, which is due to that it protects proteins against aggregation. Such luciferase co-expression system can be used as a real-time reporter to investigate the activity of chaperone proteins in vivo and provide a rapid and simple test for molecular chaperones.

5. Conclusion

In this study, it was confirmed that the expression of artemin in E. coli under heat and cold stress conditions provides significant resistance to the cells. The results from luciferase activity assay and viability experiments verify the protective role of artemin on various substrates. It is suggested that artemin can improve microbial tolerance to thermal stress through its protein and RNA chaperone activity. It is found that in co-transformed cells, the presence of artemin remarkably increased soluble luciferase levels at a temperature which is higher than its normal expressing condition. This result proposes that the presence of artemin can protect luciferase from aggregation and this feature can be utilized for a variety of recombinant proteins that are prone to aggregation in E. coli. As a suggestion, using artemin can improve the efficient storage of proteins and bacterial cells under long term storage. Future studies could develop an expression system in plant cells and estimate the ability of artemin to establish and protect cells from environmental stress for their agricultural and industrial applications.