The minimal RSV IN constructs functional in concerted integration.
A) In vitro concerted integration activities of the wild type RSV IN (1–286), the C-terminally truncated IN (1–270), and IN 1–270•C23S. The proteins were assayed for strand transfer activities using a 1.1 kb GU3 DNA substrate and with a 2.7 kb supercoiled DNA target. The concentrations (nM) of each IN are indicated at the top. The circular half-site (CHS) and concerted integration products as well as the donor substrate are indicated on the left. Lane 1 contains no IN, and in lane 11(marked M) are molecular weight markers as indicated on the right. At 18 nM IN, the percentage of donor incorporated into the concerted integration products for RSV IN 1–286, 1–270, and 1–270•C23S were 41%, 37%, and 50%, respectively. The CHS products were 10%, 9%, and 13%, respectively. The NaCl concentration in the reaction condition was 300 mM. B) Size-exclusion chromatography profiles of purified RSV IN (1–270) and IN 1–270•C23S. The proteins at 1 mg/ml were injected into a Superdex-200 column (10/300) operating with a running buffer containing 1 M NaCl. The elution positions for the molecular weight standards are indicated by arrows.