An electrophoretic characterization of iron-transporting proteins in Mannheimia haemolytica A1.

Iron-regulated outer membrane proteins (IROMPs) in Mannheimia haemolytica A1, which function as a receptor for complexes containing iron ions, are induced by iron deficiency in the growth environment of the bacteria. Densitometric analysis of SDS-PAGE separation showed expression of IROMPs of 71, 77, and 100 kDa in the case of bacteria grown in a medium with 2,2-dipyridyl. The electrophoregrams obtained in 2-DE separations confirmed the presence of protein fractions with these molecular weights and isoelectric points ranging from 5.4 to 6.4. The results of the study also confirmed the ability of M. haemolytica A1 proteins involved in iron uptake to induce a protective immune response. In Western blot with serum from convalescent calves naturally infected with M. haemolytica A1, distinct reactions were obtained for IROMPs of 71, 77, and 100 kDa.