Expression and purification of the recombinant SALT lectin from rice (Oryza sativa L.)

The SALT protein is a 14.5 kDa mannose-binding lectin, originally described as preferentially expressed in rice plant roots in response to NaCl stress. Recombinant SALT lectin was produced in Escherichia coli from a cDNA clone encoding protein. After isopropyl-beta-d-thiogalactopyranoside induction, the expression level achieved was 23% of the soluble protein. The recombinant agglutinin was purified by a single-step process by dialyses against a high concentrated salt solution. After purification, hemagglutination assays of rabbit erythrocytes revealed that the recombinant SALT protein is a potent agglutinin (0.078 microg ml(-1) minimal concentration). The purified recombinant lectin was also used for comparative estimation of native protein amounts in protein extracts from rice plants by Western blot assay.