Physical and morphological characteristics of eucaryotic ribosomes and lipopolysaccharide complexes.

Lipopolysaccharides (LPS) from Pasteurella multocida or Brucella abortus were complexed with Aspergillus fumigatus ribosomes by mixing and fixation for 3 days in 3.8% formaldehyde. To investigate the nature of their physical association, ribosomes, LPS, and ribosome-LPS complexes were (i) centrifuged in CsCl gradients to determine buoyant densities, (ii) examined by electron microscopy, and (iii) monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Ribosomes were found to bind to LPS from either P. multocida or B. abortus, producing complexes with densities of 1.45 to 1.50 g/ml. The buoyant density of the fixed ribosomes was 1.54 g/ml, and the buoyant densities of the fixed P. multocida and B. abortus LPS were 1.41 and 1.35 g/ml, respectively. Electron microscopy showed that formaldehyde-fixed ribosomes were attached to the LPS. Complexing of ribosomes to LPS may be of importance as a potentiator or carrier for experimental subunit vaccines.