A novel function of Rad54 protein: Stabilization of the Rad51 nucleoprotein filament

Alexander V. Mazin, Andrei A. Alexeev, Stephen C. Kowalczykowski

Research output: Contribution to journalArticlepeer-review

131 Scopus citations

Abstract

Homologous recombination is important for the repair of double-stranded DNA breaks in all organisms. Rad51 and Rad54 proteins are two key components of the homologous recombination machinery in eukaryotes. In vitro, Rad51 protein assembles with single-stranded DNA to form the helical nucleoprotein filament that promotes DNA strand exchange, a basic step of homologous recombination. Rad54 protein interacts with this Rad51 nucleoprotein filament and stimulates its DNA pairing activity, suggesting that Rad54 protein is a component of the nucleoprotein complex involved in the DNA homology search. Here, using physical criteria, we demonstrate directly the formation of Rad54-Rad51-DNA nucleoprotein co-complexes that contain equimolar amounts of each protein. The binding of Rad54 protein significantly stabilizes the Rad51 nucleoprotein filament formed on either single-stranded DNA or double-stranded DNA. The Rad54-stabilized nucleoprotein filament is more competent in DNA strand exchange and acts over a broader range of solution conditions. Thus, the co-assembly of an interacting partner with the Rad51 nucleoprotein filament represents a novel means of stabilizing the biochemical entity central to homologous recombination, and reveals a new function of Rad54 protein.

Original languageEnglish (US)
Pages (from-to)14029-14036
Number of pages8
JournalJournal of Biological Chemistry
Volume278
Issue number16
DOIs
StatePublished - Apr 18 2003

ASJC Scopus subject areas

  • Biochemistry

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