Envelope proteins in Neisseria.

The proteins of the cell envelope of Neisseria sicca strain ATCC 9913 have been examined by SDS - polyacrylamide gel electrophoresis. Some 20 proteins were resolved from the total envelope fraction, and nearly all of these were found to be localized in the outer membrane. Preparations of the "free-endotoxin" fraction differ from the outer membrane only in lacking a few minor proteins. The behavior of several of the envelope proteins on electrophoresis can be modified by changing the temperature of sample solubilization, and also by alteration of the growth medium. Experiments with phosphate-limited cultures showed that certain periplasmic proteins are closely associated with free endotoxin. Mutations which result in altered outer membrane permeability to antibiotics were found to cause changes in cell envelope protein composition. A comparison of the envelope proteins of eight species of non-pathogenic Neisseria showed that each had a characteristic composition. A classification of the organisms based on the relatedness of the protein patterns seen on SDS-polyacrylamide gels was in close agreement with classifications based on more usual methods.