FIG. 5.

RNase H activities catalyzed by RSV RTs. (A) Schematic representation of the heteropolymeric DNA-RNA P-T substrate comprising a 5′-end labeled 127-mer RNA to which a 36-mer DNA primer was hybridized. The major cleavage sites at positions 71 and 72 are indicated by arrows. RNase H activities of RSV RTs mutated in the RNase H active site (B) or in the polymerase active site (C) are shown. Reactions were performed for 10 min at 37°C in RT buffer with 10 nM 36-mer–127-mer DNA-RNA P-T and 10 nM enzyme. The sizes of the 5′ RNA cleavage products are indicated on the left. Lane -RT contains P-T without enzyme.