Antigen F1 from yersinia pestis forms aqueous channels in lipid bilayer membranes

ABSTRACT

Antigen F1 is a protein of 17 kDa produced by Yersinia pestis it is cultured at 37 grade C. When incorporated into planar lipid bilayer membranes this protein induces fluctuations on membrane conductance typical of the formation of ionic channels. These fluctuations reveal two distinct unitary conductance sizes, one in the range of 800 to 1400 pS and the other in the range of 140 to 600 pS. Zero current potential measaurements in the presence of a salt gradient show that the channell is not significantly ion selective. The reversal potential measured in the presence of 0.5 MKCl on the cis side and 0.1 MKCl on the trans side was 3.58 ñ 3.98 mV (N=7). The non-selectivity of the channel, in addition to its large conductance, suggests that it forms large aqueous pores. The present results, taken together with other data showing that nantigen F1 inhibits the activity of phagocytic cells, suggest that antigen F1 acts by forming aqueous pores in the membrane of these target cells