A gene fusion that localises the penicillin-binding domain of penicillin-binding protein 3 of Escherichia coli

A gene fusion that links the COOH-terminal 349 amino acids of penicillin-binding protein 3 (60 kDa) of E.coli to the NH2-terminus of β-galactosidase has been constructed. The fusion protein (38.5 kDa) retains the ability to bind benzylpenicillin with high affinity, establishing that the penicillin-binding domain (and presumably the penicillin-sensitive transpeptidase activity) of this high molecular mass penicillin-binding protein is located on a COOH-terminal functional domain.