Increased solubility of integrin βA domain using maltose-binding protein as a fusion tag

In proteomics research, generation of recombinant proteins in their native, soluble form with large quantity is often a challenging task. To tackle the expression difficulties, different expression vectors with distinct affinity fusion tags, i.e. pET-43.1a (N-utilization substance A tag), pMAL-cRI (maltose binding protein tag) (MBP tag), pGEX-4T-2 (glutathione S-transferase tag), and pET-15b (hexahistidine tag) were compared for their effects on the productivity and solubility, which were assessed by SDS-PAGE and immunoblotting, of the integrin beta A domain. The incubation temperatures were tested for its effects on these parameters. Our data suggested that MBP tag enhanced the yield and solubility of the beta A domain protein, which can also be recognized using an anti-CD 18 antibody, at room temperature incubation. Thus, the nature of fusion partner chosen for expression in bacteria and its incubation temperature would significantly affect the yield and solubility of the recombinant target protein.