Specific binding of lactoferrin to Aeromonas hydrophila

Summary

The interaction of lactoferrin (Lf) with Aeromonas hydrophila (n= 28) was tested in a ¹²⁵I-labeled protein-binding assay. The mean percent binding values for human Lf (HLf) and bovine Lf (BLf) were 13.4±2.0 (SEM), and 17.5±2.7 (SEM), respectively. The Lf binding was characterized in type strain A. hydrophila subsp. hydrophila CCUG 14551. The HLf and BLf binding reached a complete saturation within 2 h. Unlabeled HLf and BLf displaced ¹²⁵I-HLf binding in a dose-dependent manner, and more effectively by the heterologous (1 μg for 50% inhibition) than the homologous (10 μg for 50% inhibition) ligand. Apo- and holo-forms of HLf and BLf both inhibited more than 80%, while mucin caused approx. 50% inhibition of the HLf binding. Various other proteins (including transferrin) or carbohydrates did not block the binding. Two HLf-binding proteins with an estimated molecular masses of 40 kDa and 30 kDa were identified in a boiled-cell-envelope preparation, while the unboiled cell envelope demonstrated a short-ladder pattern at the top of the separating gel and a second band at approx. 60 kDa position. These data establish a specific interaction of Lf and the Lf-binding proteins seem to be porins in A. hydrophila.

Aeromonas hydrophila, Lactoferrin, Binding, Cell envelope proteins