Mutations in the 2-μm circle site-specific recombinase that abolish recombination without affecting substrate recognition

Abstract

The site-specific recombinase encoded by the yeast plasmid 2-μm circle (FLP) forms a transient covalent linkage with its sustrate DNA via a tyrosine residue, which appears to be located near its COOH terminus. The homology of the COOH terminus. The homology of the COOH terminus of FLP with that of the Int family of recombinase suggests that tyrosine-343 of FLP could be involved in forming the DNA-protein bridge. We have mutated tyrosine-343 to a phenylalanine or serine. We demonstrate that the binding of each of the two mutant proteins to its substrate is indistinguishable from that of wild-type FLP. However, both mutant proteins are incapable of catalyzing strand cleavage and recombination.