Role of the Escherichia coli recombination hotspot, χ, in RecABCD-dependent homologous pairing

Dan A. Dixon, Stephen C. Kowalczykowski

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

Genetic recombination occurring in wild type Escherichia coli is stimulated at DNA sequences known as χ sites, 5′-GCTGGTGG-3′. In vitro, homologous pairing between duplex DNA substrates dependent upon the RecA, RecBCD, and SSB proteins is stimulated by the presence of a χ sequence in the donor linear double-stranded DNA. We show that this stimulation is due to two factors: 1) the enhanced production of χ-specific single-stranded DNA fragments and 2) their preferential use in the RecA protein-promoted pairing step. Furthermore, under conditions of limiting Mg2+ concentration, joint molecule formation does not occur, even though DNA unwinding and χ-specific single-stranded DNA fragment production are observed. Also, under these conditions, χ-specific fragments derived from both the upstream and downstream regions of the DNA strand containing χ and from cleavage of the non-χ-containing DNA strand are detected. Finally, the behavior of mutant RecBCD enzymes (RecBC*D and RecBCD) in this in vitro reaction is shown to parallel their in vivo phenotypes with respect to χ stimulation of recombination. Thus we suggest that, in addition to its ability to regulate the degradative activities of RecBCD enzyme, χ itself may be a preferred site for initiation of homologous pairing in this concerted process.

Original languageEnglish (US)
Pages (from-to)16360-16370
Number of pages11
JournalJournal of Biological Chemistry
Volume270
Issue number27
StatePublished - Jul 7 1995

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Escherichia coli
Genetic Recombination
Exodeoxyribonuclease V
DNA
Single-Stranded DNA
Rec A Recombinases
DNA sequences
Joints
Phenotype
Molecules
Substrates
Proteins
In Vitro Techniques

ASJC Scopus subject areas

  • Biochemistry

Cite this

Role of the Escherichia coli recombination hotspot, χ, in RecABCD-dependent homologous pairing. / Dixon, Dan A.; Kowalczykowski, Stephen C.

In: Journal of Biological Chemistry, Vol. 270, No. 27, 07.07.1995, p. 16360-16370.

Research output: Contribution to journalArticle

Dixon, Dan A. ; Kowalczykowski, Stephen C. / Role of the Escherichia coli recombination hotspot, χ, in RecABCD-dependent homologous pairing. In: Journal of Biological Chemistry. 1995 ; Vol. 270, No. 27. pp. 16360-16370.
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