Expression, purification and characterization of galectin-1 in Escherichia coli

• We highly expressed recombinant Gal-1 and Gal-1②② concatemer in Escherichia coli.
• Both molecules were purified by ion-exchange chromatography with high efficiency.
• Both Gal-1 and Gal-1②② exhibited hemagglutinating activity.
• Gal-1 and Gal-1②② apparently inhibit the proliferation of human leukemia cells.
• The bioactivity of Gal-1②② was stronger than that of Gal-1.

As a member of beta-galactoside-binding proteins family, Galectin-1 (Gal-1) contains a single carbohydrate recognition domain, by means of which it can bind glycans both as a monomer and as a homodimer. Gal-1 is implicated in modulating cell–cell and cell–matrix interactions and may act as an autocrine negative growth factor that regulates cell proliferation. Besides, it can also suppress TH1 and TH17 cells by regulating dendritic cell differentiation or suppress inflammation via IL-10 and IL-27. In the present study, Gal-1 monomer and concatemer (Gal-1②②), which can resemble Gal-1 homodimer, were expressed in Escherichia coli   and their bioactivities were analyzed. The results of this indicate that both Gal-1 and Gal-1②② were expressed in E. coli   in soluble forms with a purity of over 95% after purifying with ion-exchange chromatography. Clearly, both Gal-1 and Gal-1②② can effectively promote erythrocyte agglutination in hemagglutinating activity assays and inhibit Jurkat cell proliferation in MTT assays. All these data demonstrate that bacterially-expressed Gal-1 and Gal-1②② have activities similar to those of wild type human Gal-1 whereas the bioactivity of concatemer Gal-1②② was stronger than those of the bacterially-expressed and wild type human Gal.