[Selective solubilization and biochemical analysis of R. prowazekii outer membrane proteins].

Solubilization of proteins from total membranes (a mixture of cytoplasmic and outer membranes) of Rickettsia prowazekii, a typical gram-negative bacterium, was studied using three different detergents. It was shown that isolated outer membranes and sarkosyl-insoluble material contain major polypeptides of 134, 31, 29.5 and 25 kDa as well as minor polypeptides of 78, 60, 42, and 17 kDa, while the total membranes--the same plus a great number of additional minor proteins. The material solubilized by octyl glucoside in the presence of MgCl2 contains exclusively major proteins (134, 31, 29.5, and 25 kDa). No differential solubilization takes place upon membrane treatment with octyl glucoside in the absence of Mg2+ or with Triton X-100. Rickettsial proteins are insensitive to trypsin in both whole cells and total membranes, unless the latter are presolubilized with octyl glucoside. Proteinase K degrades all of the total membrane proteins but only the 134 kDa polypeptide of whole cells. Upon immunoblotting predominantly the major outer membrane proteins (134, 31, and 20.5 kDa) and, to a lesser extent, the minor proteins (60, 42, and 17 kDa) interact with human convalescent serum.