Figure 2.

Kinetic analysis of donor strand exchange at 25°C. (A–E) The FimC_His:FimA complex was incubated either alone or with FimA_A, a mixture of FimA_A and FimC_His or the donor strand of FimA (DS_FimA). After different reaction times, the concentrations of FimC_His:FimA and free FimC_His were measured by ion-exchange chromatography (filled circles and triangles, respectively). The solid lines represent fits to a second-order reaction (complex alone) or parallel second-order and pseudo-first-order reactions (all other reactions). (F–H) DSE reaction schemes. Components with the attacking donor strand are coloured and the FimC_His:FimA complex under attack is depicted in grey. In (F), the two alternative mechanisms of DSE are shown for the reaction in which FimC_His:FimA alone undergoes DSE. When FimA_A or DS_FimA is also present, parallel reactions occur (G,H). DSE, donor strand exchange.