Fig 4.

The strand exchange caused by ZfL2-1 ORF1p is reversible. Strand exchange assays were performed in the presence of Trx or the Trx fusion of the N-terminal portion of ZfL2-1 ORF1p (Trx-N-ORF1p). (A to E) Schematic diagrams of the strand exchange assays are shown. Oligonucleotides used in the assays are indicated by blue and red lines. Their sequences are shown in Table 2. One strand of each initial duplex was labeled by ³²P at its 5′ end (asterisks). (F) Time course for the single-stranded fraction of the labeled oligonucleotides in the strand exchange assays (A to D). Filled symbols indicate values with Trx-N-ORF1p; open symbols indicate values with Trx. The strand exchanges were conducted with 1 μM proteins at 37°C. Five independent experiments were performed, and the averages and standard deviations are shown. (G) Time course for the single-stranded fraction of the labeled oligonucleotide in the strand exchange assay (E). Filled and open symbols are as described for panel F. (H) Time course for the single-stranded fraction of the labeled oligonucleotide in strand exchange assays. The strand exchange assay (D) was conducted with (+) or without (−) addition of a 50-fold excess co29. co29 was added at 20 min after the initiation (dashed line). Filled and open symbols are as described for panel F. (I) The initial rates of the strand exchange reactions (A to D). The averages of the initial rates and standard deviations are indicated. Statistical analysis was performed using Student's t test; *, P < 0.05; ***, P < 0.001.