FIG. 6.

Strand-exchange activity of ORF1p. (A) Preannealed duplex DNA (29-[³²P]-mm29c [1 nM]) was challenged with 50 nM c29 in the presence or absence of ORF1p made in E. coli. (B) The times of incubation and concentrations of protein are indicated. For this reaction, the two duplexes, 29-c29 and 29-mm29c, are not resolved by size, and only mm29c is labeled with ³²P. Thus, the exchange reaction leads to the disappearance of the 29-[³²P]mm29c duplex and the appearance of single-stranded [³²P]mm29c. The two major bands resolved in this gel are the 29-[³²P]mm29c duplex and the denatured form of [³²P]mm29c. The minor band, migrating slower than the duplex, is a structured form of the single-stranded [³²P]mm29c (see Results).