Figure 5.

Unstable synaptic complexes form with cleavage-deficient Int mutants. (A) Changes in the effective lengths of single attL+attR molecules in response to the addition of recombination proteins IntK235A, Xis, and IHF. (B, C) Lifetime distributions from all single-molecule records after the addition of IntK235A, Xis, and IHF to attL+attR molecules: lifetimes of (B) initial presynaptic and (C) synaptic complexes formed with IntK235A. The lifetime τ for each distribution was determined by fitting to a scaled exponential probability function. The reciprocal of τ is the apparent rate constant for synapsis of IntK235A-containing presynaptic complexes (B) or the apparent rate constant for desynapsis of IntK235A-containing synaptic complexes (C). (D) Lifetimes of the desynapsed population formed after IntK235A-mediated synapsis (e.g., 11–26 min in panel A). The parameters τ₁, τ₂, and A were determined by fitting to a scaled biexponential probability function and determine the rate constants for resynapsis (see Discussion).