Pae χψ interacts with ssDNA that is covered by Eco SSB+Gly. Pae χψ (diamonds) or Eco χψ (triangles) were titrated to a saturated Eco SSB+Gly/poly(dT) complex containing 1 μM SSB and 35 μM dT in low salt buffer. The mixtures were sedimented at 22000 rpm and 20°C, with λ = 280 nm. Lines are drawn just to guide the eye. Whereas the addition of Eco χψ has only a slight effect that might be due to the binding of Eco χψ to Eco SSB+Gly, Pae χψ increases the sedimentation coefficient from 20 S to about 34 S, indicating that Pae χψ is able to bind to ssDNA even when the latter is saturated with SSB proteins.