Hybridization of Variants of Chloramphenicol Acetyltransferase Specified by fi + and fi - R Factors

Abstract
An fi(-) type of R factor for transferable chloramphenicol resistance carries the structural gene for a novel species of chloramphenicol acetyltransferase (EC 2.3.1.99). The enzyme associated with the fi(-) plasmid is distinct from that described for fi(+) R factors. The fi(+)- and fi(-)-related variants of chloramphenicol acetyltransferase were hybridized in vivo and in vitro. Both techniques yielded only a single symmetrical heteromeric species rather than the three (A(3)B(1), A(2)B(2), and A(1)B(3)) hybrids predicted from the tetrameric (identical monomers) structure of chloramphenicol acetyltransferase.