Q beta replicase containing a Bacillus stearothermophilus elongation factor.

We purified Q beta replicase containing EF-Ts from Bacillus stearothermophilus in place of the homologous polypeptide from Escherichia coli. The hybrid enzyme was fully active in the transcription of a variety of templates. It was found to be qualitatively similar to native Q beta replicase with respect to a variety of parameters which measure the efficiency of initiation of RNA synthesis. The results demonstrated that Q beta replicase can tolerate substantial alterations in the EF-Tu X Ts component of the enzyme. These alterations resulted in only minor perturbations of catalytic properties.