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Action of site‐specific recombinases XerC and XerD on tethered Holliday junctions
Author(s) -
Arciszewska Lidia K.,
Grainge Ian,
Sherratt David J.
Publication year - 1997
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/16.12.3731
Subject(s) - holliday junction , recombinase , biology , recombination , dna , branch migration , site specific recombination , biophysics , binding site , flp frt recombination , integrases , stereochemistry , homologous recombination , genetics , chemistry , genetic recombination , base sequence , gene
In Xer site‐specific recombination, two related recombinases, XerC and XerD, mediate the formation of recombinant products using Holliday junctioncontaining DNA molecules as reaction intermediates. Each recombinase catalyses the exchange of one pair of specific strands. By using synthetic Holliday junction‐containing recombination substrates in which two of the four arms are tethered in an antiparallel configuration by a nine thymine oligonucleotide, we show that XerD catalyses efficient strand exchange only when its substrate strands are ‘crossed’. XerC also catalyses very efficient strand exchange when its substrate strands are ‘crossed’, though it also appears to be able to mediate strand exchange when its substrate strands are ‘continuous’. By using chemical probes of Holliday junction structure in the presence and absence of bound recombinases, we show that recombinase binding induces unstacking of the bases in the centre of the recombination site, indicating that the junction branch point is positioned there and is distorted as a consequence of recombinase binding.