FIGURE 9.

Initial rate of coupled concerted integration using blunt-ended GU3 substrate was controlled by length of tail region. The concerted integration activity of each RSV IN construct was determined with a blunt-ended 20B GU3 substrate (A). Strand transfer was carried out with each respective IN (top) (2 μm) and DNA (1 μm) at 37 °C for 5, 10, and 15 min. Products were deproteinized and run on a 1.8% agarose gel. Lane 1, marked “M,” contains the molecular size markers (Promega kb ladder). Lane 20, marked “C,” does not contain any IN. Concerted products were quantified by a Typhoon 9500 laser scanner, and the -fold difference in activity relative to IN(1–269) was plotted (B). The colors of each IN are indicated. The standard deviation (error bars) was determined from at least three independent experiments. C and D are the same as A and B except 3′-OH recessed 18R GU3 was used. CHS, circular half-site; S.C., supercoiled; O.C., open circular.