Construction and characterization of a tufA-lacZ fusion coding for an E. coli EF-Tu-beta-galactosidase chimeric protein.

A new phage lambda cloning vector was constructed that has a single EcoRI site upstream from weakly expressed lacI-Z gene isolated by Müller-Hill and Kania (1974). An EcoRI fragment containing the complete tufA gene of E. coli was cloned on the vector and the recombinant phage was crossed into the str operon that has tufA as its last gene. Subsequent selection gave rise to a tufA-lacZ fusion that codes for a chimeric peptide. The fused peptide has a molecular weight of 148,000 and contains 40% of the N-terminal of EF-Tu followed by part of the lac repressor-beta-galactosidase fusion. The specific activity of the fused peptide is about half of the activity of normal beta-galactosidase.