Purification of a maize dehydrin protein expressed in Escherichia coli

A maize dehydrin protein (Dhn1) containing 167 amino acids with a predicted molecular weight of 17.0 kDa was produced in the Escherichia coli overexpression strain BL21 (DE3)pLysS. Site-directed mutagenesis was used to construct a plasmid with a protein coding region corresponding exactly to the original cDNA. Protein production was induced by IPTG. Dhn1 was enriched from total soluble protein by heat-fractionation and centrifugation and then purified by sequential cation exchange and hydrophobic interaction chromatography. The purified protein was visualized by SDS-PAGE and immunoblot analysis using a polyclonal antibody to the dehydrin consensus region. Expression in E. coli resulted in approximately 1.2 mg of purified protein per liter of induced culture.