A kinetic model for binding protein-mediated arabinose transport.

A kinetic model is presented based on the simplest plausible mechanism for bacterial binding protein-dependent transport. The transport phenotypes of the 18 variant arabinose-binding proteins analyzed by Kehres and Hogg (1992, Protein Sci. 1, 1652-1660) (wild type and 17 mutants) are interpreted to mean that in wild-type arabinose uptake the forward transport rate (k(for)) greatly exceeds the dissociation rate (kund) of a binding protein docked with the AraG:AraH membrane complex, and that k(for) dominance is preserved in all of the binding protein surface mutants. The assumptions and predictions of the model are consistent with existing data from other periplasmic transport systems.