Suicide recombination substrates yield covalent lambda integrase-DNA complexes and lead to identification of the active site tyrosine.
High levels of covalent integrase-DNA complexes accumulate when suicide substrates containing a medial nick within the overlap region are nicked by lambda integrase protein. The tyrosine residue at position 342 is shown to form a covalent bond with DNA at the sites of strand exchange. A mutant integrase in which this tyrosine is changed to phenylalanine is devoid of both topoisomerase and recombinase activity but still binds to both core- and arm-type DNA binding sites with an affinity comparable to wild-type integrase. Tyrosine-342 is located within a 40-amino acid region that is conserved among 15 known recombinases comprising the "integrase family." The present results show that this small region of homology participates in catalysis of strand transfer.
Pargellis
C A
CA
Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912.
Nunes-Düby
S E
SE
de Vargas
L M
LM
Landy
A
A
D000595:Amino Acid Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D004254:DNA Nucleotidyltransferases / Q000378:metabolism*; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D019426:Integrases; D008969:Molecular Sequence Data; D014443:Tyrosine / Q000378:metabolism*
D014443:Tyrosine; D004247:DNA; D004254:DNA Nucleotidyltransferases; D019426:Integrases; D004264:DNA Topoisomerases, Type I