Major outer membrane proteins of Escherichia coli strains of human origin.

The major outer membrane protein patterns of 45 Escherichia coli strains of human origin were compared with that of E. coli K12 by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Preparations of the former strains contained between two and five major bands in the molecular weight range between 30 000 and 42 000. The patterns were very heterogeneous with respect to the numbers and electrophoresis mobilities of the major outer membrane protein bands. In all cases the fastest moving band was characterized as a protein similar to the ompA protein of strain K12 as it was partially degraded by trypsin and reacted specifically with antiserum against the purified omp A protein in a gel immuno-radioassay. All the other major outer membrane proteins are related to the ompC and ompF proteins (the porins) of strain K12 as they were peptidoglycan-associated and reacted with antisera against the purified ompC and/or ompF proteins.