Figure 4.

DNA circularisation by LrpC. The 182 bp [γ-³²P]DNA fragment (0.5 nM) was incubated with increasing concentrations of the LrpC protein (30–500 nM, lanes 2–6 and 8–12) in buffer C containing 50 mM NaCl and 1 mM ATP for 15 min at 37°C. In samples 1–6 the DNA was further incubated with ligase buffer and in lanes 7–12 with 1 U of T4 DNA ligase for 30 min at 16°C. The samples were deproteinised and analysed by 4% non-denaturing PAGE in 0.5× TBE, and autoradiographs of the dried gels were subsequently taken.