SPECIFIC HIGH-AFFINITY BINDING OF HUMAN INTERLEUKIN-1-BETA BY CAF1A USHER PROTEIN OF YERSINIA-PESTIS

Understanding the interaction of Yersinia pestis with the key componen ts of the immune system is important for elucidation dation of the pat hogenesis of bubonic plague, one of the most severe and acute bacteria l diseases, Here we report the specific, high affinity binding (K-d = 1.40 x 10(-10) M +/- 0.14 x 10(-10)) of radiolabelled human interleuki n 1 beta (hIL-1 beta) to E. coli cells carrying the capsular f1 operon of Y. pestis. Caf1A outer membrane usher protein was isolated to grea ter than 98% purity. Competition studies with purified Caf1A, together with immunoblotting studies, identified Caf1A as the hIL-1 beta recep tor. Competition between Caf1 subunit acid hIL-1 beta for the same or an overlapping binding site on Caf1A was demonstrated. Relevance of th ese results to the pathogenesis of Y. pestis and other Gram negative b acterial pathogens with homologous outer membrane usher proteins is di scussed.