Mutations in the amino-terminal domain of lambda-integrase have differential effects on integrative and excisive recombination.
Lambda integrase (Int) forms higher-order protein-DNA complexes necessary for site-specific recombination. The carboxy-terminal domain of Int (75-356) is responsible for catalysis at specific core-type binding sites whereas the amino-terminal domain (1-70) is responsible for cooperative arm-type DNA binding. Alanine scanning mutagenesis of residues 64-70, within full-length integrase, has revealed differential effects on cooperative arm binding interactions that are required for integrative and excisive recombination. Interestingly, while these residues are required for cooperative arm-type binding on both P'1,2 and P'2,3 substrates, cooperative binding at the arm-type sites P'2,3 was more severely compromised than binding at arm-type sites P'1,2 for L64A. Concomitantly, L64A had a much stronger effect on integrative than on excisive recombination. The arm-binding properties of Int appear to be intrinsic to the amino-terminal domain because the phenotype of L64A was the same in an amino-terminal fragment (Int 1-75) as it was in the full-length protein.
Warren
David
D
Division of Biology and Medicine, Brown University, Providence, RI 02912, USA.
Lee
Sang Yeol
SY
Landy
Arthur
A
D001483:Base Sequence; D002876:Chromosomes, Bacterial / Q000235:genetics; D018983:DNA Footprinting; D004269:DNA, Bacterial / Q000235:genetics; D003850:Deoxyribonuclease I; D004926:Escherichia coli / Q000201:enzymology; D019426:Integrases / Q000235:genetics* / Q000378:metabolism*; D016296:Mutagenesis; D017384:Sequence Deletion
D004269:DNA, Bacterial; D019426:Integrases; D003850:Deoxyribonuclease I