Figure 6. Critical role of the amino acid residue W259 in RSV IN.

A) RSV IN constructs 1–270 and 49–270, and their W259A mutants, were assayed at the indicated concentrations (top) for stand transfer activities. The GU3 3.6 kb donor was used. The CHS and concerted integration products are indicated on the right. Markers are in lane 1 and the control (minus IN) is lane 2. The NaCl concentration in the reaction condition was 100 mM. B) The 3′ OH processing activity for these above constructs as well as wild type RSV IN (1–286) are shown. All of the assays contained 20 nM IN and either MgCl₂ or MnCl₂ as indicated. C) Integration activities of RSV IN (1–270) with W259T or W259R amino acid substitution, tested at two different NaCl concentrations. D) 3′-end processing activities of the W259T and W259R mutants, tested in the presence of either Mg²⁺ or Mn²⁺. Both mutants are completely inactive. E) Size-exclusion chromatography profile of RSV IN (1–270)•W259A, overlaid with that of RSV IN(1–270).