Localization of major, high molecular weight proteins in Bacteroides forsythus

Bacteroides forsythus produces species-specific major proteins with high mo lecular weights of 270 and 230-kDa (270K and 230K), A specific antibody rai sed against 270K was used for Western blot analysis and immunoelectron micr oscopy, Western blot analysis showed that the 270K and 230K proteins were i mmunologically similar. Immunogold labeling of ultrathin-sectioned bacteria l cells and biochemical fractionation revealed that these proteins were loc alized at the outermost cell surface, not in the cytoplasm, These results s uggest that major proteins ubiquitous to this species may form the S-layer.