Purification of recombinant Arabidopsis thaliana dehydrins by metal ion affinity chromatography

In this study we describe a novel method for purification of Arabidopsis th aliana dehydrins overproduced in Escherichia coli. The cDNAs corresponding to the four dehydrin genes RAB18, LTI29, LTI30, and COR47 were inserted int o a bacterial expression vector under an isopropyl beta -D-thiogalactopyran oside (IPTG) inducible bacterial promoter. After IPTG induction all four pr oteins accumulated in high amounts. The recombinant proteins were efficient ly purified to over 95% purity with a three-step purification scheme: heat fractionation, immobilized metal ion affinity chromatography (IMAC), and io n exchange chromatography, In this study we introduce the novel use of IMAC as an efficient purification method for native dehydrins. Characterization of the purified proteins was done by Edman degradation, mass spectrometry, reverse-phase chromatography, and analytical gel filtration under native a nd denaturing conditions. Yields of purified proteins were between 2.8 and 12.5 mg per liter of bacterial culture, sufficient for further biochemical studies. (C) 2000 Academic Press.