Volume 270,
Number 39,
Issue of September 29, pp. 23044-23054, 1995
©1995 by The American Society for Biochemistry and Molecular Biology, Inc.
Cleavage-dependent
Ligation by the FLP Recombinase
CHARACTERIZATION OF A MUTANT FLP PROTEIN WITH AN ALTERATION IN A
CATALYTIC AMINO ACID
(Received for publication, March 23,
1995; and in revised form, July 20, 1995)
Xu-Dong
Zhu ,
Paul D.
Sadowski
The FLP recombinase of the 2 µM plasmid of Saccharomyces cerevisiae belongs to the integrase family of
recombinases whose members have in common four absolutely conserved
residues (Arg-191, His-305, Arg-308, and Tyr-343). We have studied the
mutant protein FLP R308K in which the arginine residue at position 308
has been replaced by lysine. Although FLP R308K was previously reported
to be defective in ligation of certain substrates (Pan, G., Luetke, K.,
and Sadowski, P. D., Mol. Cell. Biol. 13, 3167-3175,
1993b), we show in this work that the protein is able to ligate those
substrates that it can cleave (cleavage-dependent ligation activity).
FLP R308K is defective in in vitro recombination and in strand
exchange. It is able to carry out strand exchange at one of the two
cleavage sites of the FLP recognition target site (FRT site), but is
defective in strand exchange at the other cleavage site. These results
are consistent with a model in which wild-type FLP initiates
recombination only at one of the two cleavage sites. FLP R308K may be
defective in the initiation of recombination.