RESUMO
Purified outer membrane proteins (OMP) of Salmonella minnesota, Re-form, were incorporated into liposomes. These induced in macrophages a chemiluminescence signal identical to that of the intact Re-form. This signal was abolished by preincubation of porin-containing liposomes with purified C1q. Incorporation of isolated OMP into black lipid membranes (BLM) resulted in channel-formation which could not be inhibited by isolated C1q. Additionally, incubation of OMP-containing liposomes with BLM resulted in pore-formation within the BLM. This was amplified when lipid A was present within the liposomes. Preincubation of OMP-containing liposomes with purified C1q abolished pore-formation within the BLM.
Assuntos
Proteínas da Membrana Bacteriana Externa/metabolismo , Complemento C1q/metabolismo , Canais Iônicos/fisiologia , Salmonella/metabolismo , Animais , Proteínas da Membrana Bacteriana Externa/isolamento & purificação , Células Cultivadas , Colesterol , Complemento C1q/isolamento & purificação , Condutividade Elétrica , Humanos , Cinética , Bicamadas Lipídicas , Luminescência , Macrófagos/fisiologia , Potenciais da Membrana , Membranas Artificiais , Camundongos , Camundongos Endogâmicos BALB C , Fosfatidilcolinas , PorinasRESUMO
Porins of Salmonella minnesota, R595, were purified by anion exchange chromatography and subsequently isolated in their monomeric form by chromatofocusing. Two forms of porin could be isolated, both with an apparent molecular mass of 37,000, but of differing isoelectric points (pI 4.6 versus pI of 4.9). Porins with pI 4.9 did not contain any detectable LPS, but porins with pI 4.6 were found to contain trace amounts of LPS (1.3 x 10(-4) micrograms LPS/1 microgram porin) as measured using a highly sensitive limulus assay. Unlike the LPS-associated porins the monomeric porins were biologically inert with regard to pore formation, but they were still able to bind C1q, a subcomponent of the first component of complement.