Facile production and rapid purification of functional recombinant Qβ replicase heterotetramer complex

We describe an improved method for the production of recombinant Qβ replicase heterotetramer. The successful expression of the soluble Qβ RNA polymerase complex depends on the EF-Ts and EF-Tu subunits being co-expressed prior to β-subunit expression. Efficient co-expression requires two different inducible operons to co-ordinate the expression of the heterotrimer. The complete heterotetramer enzyme complex is achieved by production of the recombinant S1-subunit of Qβ replicase in a separate host. This approach represents a facile way for producing and purifying large amounts of soluble and active recombinant Qβ replicase tetramer without the necessity of a His-tag for purification.