Fig. 1.

HsRad52 protein promotes strand exchange. Reactions were carried out as described in Materials and Methods. The oligonucleotide G16(-)(6 μM) was preincubated for 10 min with the indicated amounts of HsRad52 at 37°C, followed by addition of 2.5 μM homologous duplex oligonucleotide (5′-labeled with ³²P on the minus strand). After 40 min, the reactions were stopped and analyzed by electrophoresis in 15% polyacrylamide and 0.5× TBE buffer (see Materials and Methods). The ³²P-labeled ssDNA product was quantified by PhosphorImager analysis. Lane 1, no ssDNA; lane 2, heterologous ssDNA derived from the G16(-) oligonucleotide by making nine transversion mismatches; lane 3, no Rad52 protein; and lanes 4–7, increasing amounts of Rad52 as indicated. (At concentrations of Rad52 <0.4 μM, the yields decreased.)