Abstract
Homologous recombination (HR) machinery is composed of so-called Rad52 epistasis group proteins in eukaryotes. In plant kingdom, none of the genes located downstream of HR proteins have been isolated. Here, we characterized Snf2p/Swi2p family genes, OsRad54 and OsRad54B, and XPF endonuclease superfamily gene, OsMus81. Transient expressin of GFP::OsRad54 and GFP::OsRad54B cDNAs localized GFP-fluorescence exclusively in onion nuclei, suggesting their role(s) in nuclei. RT-PCR analysis revealed that OsRad54 and OsMus81 were induced by gamma-ray causing double strand breaks. Yeast two-hybrid analysis detected strong protein-protein interactions in OsRad51A1-OsRad54 and OsRad54-OsMus81 pairs, moderate interaction in OsRad51A1-OsRad54B, but not in OsRad54B-OsMus81. These results implied important roles of OsRad54 DNA-helicase protein as a bridge between DNA-exchanging reaction with OsRad51A1 and crossover formation with OsMus81 in the HR process. Biochemical analyses are in progress to elucidate precise functions of those proteins.
