DNA condensation by VP19C.

<p>The morphology of the VP19C-DNA complexes was analyzed by electron microscopy. Purified VP19C (150 µg) was mixed with the BamH1 K DNA (250 ng) substrate and the NPC examined after 15 min of incubation. In panel A, full-length VP19C was mixed with DNA. Toroids of different sizes were detected and are indicated by black arrows. In panel B, VP19C N-ter⁷² was incubated with DNA. DNA loop structures (white arrowheads) along with aggregated condensed DNA (marked by black arrows) were induced by VP19C N-ter⁷². Shown in panel C and D is the morphology of DNA in the presence of GST protein or no added protein, respectively. Scale bars are 100 nm and 10 nm for panel A inset.