The ferrichrome-iron receptor of Escherichia coli K-12. Antigenicity of the fhuA protein.

The ferrichrome-iron receptor in the outer membrane of Escherichia coli K-12 was isolated by preparative SDS-polyacrylamide gel electrophoresis and electroelution of the protein from the gel into solution. This protein, called the fhuA (=tonA) gene product, was biologically active in non-ionic detergent solutions because it was able to inactivate T5 phages. Antibodies were raised against fhuA protein by injecting rabbits with isolated material in polyacrylamide chips. Titers of specific immunoglobulin were confirmed by microenzyme-linked immunosorbent assay. The gamma globulin fraction of anti-fhuA protein completely blocked the adsorption of T5 phage, and partially inhibited ferrichrome-promoted iron uptake.