Figure 8.

(A) Schematic map (not to scale) of the WRNp domain structure and the mutations in the WRN-ΔR and WRN-K577M proteins. Domains are depicted by uniquely shaded boxes as indicated and an asterisk marks the site of the amino acid (a.a.) change in helicase motif I of WRN-K577M. (B) Effect of addition of wt WRN and mutant proteins on RNA pol II transcription. The effect of addition of wt WRNp and mutant proteins (WRN-ΔR andWRN-K577M) on the transcription from the AdML promoter by nuclear extracts from wild-type SNW646 was assayed as described earlier. Reactions contained 75 μg of nuclear extract to which 50 ng of WRN (wt) or mutant proteins (WRN-ΔR or WRN-K577M) were added. As a control, an equivalent amount of the mock-purified protein preparation was used in one reaction. The reactions were incubated at 30°C for 1 h, and transcription was monitored by electrophoresis and phosphorimaging. Similar results were observed in at least three independent experiments.