Identification of PlantRAD52Homologs and Characterization of theArabidopsis thaliana RAD52-Like Genes

Abstract

RADiation sensitive52 (RAD52) mediates RAD51 loading onto single-stranded DNA ends, thereby initiating homologous recombination and catalyzing DNA annealing. RAD52 is highly conserved among eukaryotes, including animals and fungi. This article reports that RAD52 homologs are present in all plants whose genomes have undergone extensive sequencing. Computational analyses suggest a very early RAD52 gene duplication, followed by later lineage-specific duplications, during the evolution of higher plants. Plant RAD52 proteins have high sequence similarity to the oligomerization and DNA binding N-terminal domain of RAD52 proteins. Remarkably, the two identified Arabidopsis thaliana RAD52 genes encode four open reading frames (ORFs) through differential splicing, each of which specifically localized to the nucleus, mitochondria, or chloroplast. The A. thaliana RAD52-1A ORF provided partial complementation to the yeast rad52 mutant. A. thaliana mutants and RNA interference lines defective in the expression of RAD52-1 or RAD52-2 showed reduced fertility, sensitivity to mitomycin C, and decreased levels of intrachromosomal recombination compared with the wild type. In summary, computational and experimental analyses provide clear evidence for the presence of functional RAD52 DNA-repair homologs in plants.

The Arabidopsis SWR1 Chromatin-Remodeling Complex Is Important for DNA Repair, Somatic Recombination, and Meiosis

“…Defects in gametogenesis are frequently observed in mutants impaired in meiosis (Li et al, 2004;Siaud et al, 2004;Samach et al, 2011). Therefore, we compared different stages of meiotic progression after 49,6-diamidino-2-phenylindole (DAPI) staining Error bars correspond to the SE.…”

Mechanism of Homologous Recombination and Implications for Aging-Related Deletions in Mitochondrial DNA

“…Like in yeast, mitochondria in Arabidopsis thaliana also express a short version of a Rad52-related protein similar to Mgm101, known as Rad52-1B (Fig. 6A) (180). Gualberto and coworkers independently identified Rad52-1B as ODB1 (organellar DNA binding protein 1) based on its DNA binding activity.…”

The Recombinases DMC1 and RAD51 Are Functionally and Spatially Separated during Meiosis in Arabidopsis

“…Regulation of recombinase loading is different in higher eukaryotes (including plants), because, for instance, BRCA2 (a protein not found in yeast) is essential for RAD51 loading (Siaud et al, 2004) (reviewed in San Filippo et al, 2008. Other proteins instrumental for loading of Rad51 or Dmc1 in yeast, like the Mei5/ Sae3 complex, have not been found in Arabidopsis (Ray and Langer, 2002;Liu and Heyer, 2011), and the molecular function of the recently discovered RAD52-like proteins has not yet been defined (Samach et al, 2011). In yeast, Rad51 and Dmc1 proteins have been found to localize side-by-side in some wellspread meiotic nuclei (Shinohara et al, 1997;Shinohara et al, 2000).…”