Conformational states and association mechanism of Yersinia pestis Caf1 subunits

Bacterial infectivity often relies on efficient attachment to the host cells through adhesive extensions. Unveiling the structural basis of the formation of these organelles is of paramount importance for both academic and applicative implications. Computational approaches may fruitfully complement experimental studies by providing information on specific conformational states whose characterization is difficult. Here, we report molecular dynamics characterizations of Yersinia pestis Caf1 subunit in its monomeric-unbound and dimeric states. Data on the monomeric form indicate that it is highly reactive and evolves toward compact states, which likely hamper subunit-subunit association. In line with recent experimental reports, this finding implies that chaperone release and subunit-subunit association must be simultaneous. MD analysis on Caf1 dimer lead to the formation of a novel assembly endowed with a significant stability in the simulation timescale. Using these data, an end-to-end model of the fiber, which well agrees with available experimental data, was also generated.