The human Rad52 protein exists as a heptameric ring

Alicja Z. Stasiak, Eric Larquet, Andrzej Stasiak, Shirley Müller, Andreas Engel, Eric Van Dyck, Stephen C. West, Edward H. Egelman*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

157 Citations (Scopus)

Abstract

The RAD52 epistasis group was identified in yeast as a group of genes required to repair DNA damaged by ionizing radiation [1]. Genetic evidence indicates that Rad52 functions in Rad51-dependent and Rad51-independent recombination pathways [2-4]. Consistent with this, purified yeast and human Rad52 proteins have been shown to promote single-strand DNA annealing [5-7] and to stimulate Rad51-mediated homologous pairing [8-11]. Electron microscopic examinations of the yeast [12] and human [13] Rad52 proteins have revealed their assembly into ring-like structures in vitro. Using both conventional transmission electron microscopy and scanning transmission electron microscopy (STEM), we found that the human Rad52 protein forms heptameric rings. A three-dimensional (3D) reconstruction revealed that the heptamer has a large central channel. Like the hexameric helicases such as Escherichia coli DnaB [14,15], bacteriophage T7 gp4b [16,17], simian virus 40 (SV40) large T antigen [18] and papilloma virus E1 [19], the Rad52 rings show a distinctly chiral arrangement of subunits. Thus, the structures formed by the hexameric helicases may be a more general property of other proteins involved in DNA metabolism, including those, such as Rad52, that do not bind and hydrolyze ATP.

Original languageEnglish
Pages (from-to)337-340
Number of pages4
JournalCurrent Biology
Volume10
Issue number6
DOIs
Publication statusPublished - 1 Mar 2000
Externally publishedYes

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