Interdomain interaction in the FimH adhesin of Escherichia coli regulates the affinity to mannose.

摘要: FimH is a mannose-specific adhesin located on the tip of type 1 fimbriae Escherichia coli that capable mediating shear-enhanced bacterial adhesion. consists fimbria-associated pilin domain and mannose-binding lectin domain, with binding pocket positioned opposite interdomain interface. By using yeast two-hybrid system, purified domains, docking simulations, we show here domains interact one another. The affinity for mannose greatly enhanced (up to 300-fold) in variants which interaction disrupted by structural mutations either or domains. Also, dramatically isolated complexed chaperone molecule wedged between Furthermore, native structure mediates weak at low shear stress but shifts strong high shear, whereas contacts (or domain) mannose-coated surfaces even under shear. We propose interactions decrease via an allosteric mechanism. further suggest mechanical force separates two allowing switch from state. This shift provides mechanism FimH-mediated adhesion enabling form catch bond-like are longer lived tensile force.