RecR protein, a functional equivalent of Rad52 in eukaryotes, plays a critical role in the Reef pathway of homologous recombination in Escherichia coli. By constructing and expressing the recR-yfp hybrid gene, the distribution of the RecR-YFP fusion protein was visu-alized in E. coli by fluorescent microscopy. Our results showed that RecR proteins can be localized predominantly in the nucleoid region of E. coli. By measuring the UV resistance of a recR mutant carrying the recR-yfp gene in the plasmid, the expressed RecR-YFP was found to be functional in improving the UV resistance of the recR deficiency strain.