Figure 3.

Coexpression of GST–mjF and mjE subunits in E.coli. (A) Schematic representation of the expression constructs used. (B) Comparison of the protein expression profiles of bacterial cells harboring the constructs illustrated above. The insoluble and soluble fractions, together with GCE, are shown for the GST–mjF (lanes 1, 4 and 7), GST–mjE (lanes 2, 5 and 8) and GST–mjF/mjE (lanes 3, 6 and 9) expression strains. The GST–mjE fusion protein is highly insoluble when expressed on its own and is thus exclusively present in the pellet fractions (lane 2). The bicistronic construct expressing GST–mjF and mjE leads, however, to the formation of a heterodimeric complex with increased solubility that can be purified by glutathione affinity chromatography (lane 9).