Recognition roles of the carbohydrate glycotopes of human and bovine lactoferrins in lectin–N-glycan interactions

BackgroundLactoferrin is an iron-binding protein belonging to the transferrin family. In addition to iron homeostasis, lactoferrin is also thought to have anti-microbial, anti-inflammatory, and anticancer activities. Previous studies showed that all lactoferrins are glycosylated in the human body, but the recognition roles of their carbohydrate glycotopes have not been well addressed.MethodsThe roles of human and bovine lactoferrins involved in lectin–N-glycan recognition processes were analyzed by enzyme-linked lectinosorbent assay with a panel of applied and microbial lectins.Results and conclusionsBoth native and asialo human/bovine lactoferrins reacted strongly with four Man-specific lectins — Concanavalia ensiformis agglutinin, Morniga M, Pisum sativum agglutinin, and Lens culinaris lectin. They also reacted well with PA-IIL, a LFuc>Man-specific lectin isolated from Pseudomonas aeruginosa. Both human and bovine lactoferrins also recognized a sialic acid specific lectin-Sambucus nigra agglutinin, but not their asialo products. Both native and asialo bovine lactoferrins, but not the human ones, exhibited strong binding with a GalNAc>Gal-specific lectin-Wisteria floribunda agglutinin. Human native lactoferrins and its asialo products bound well with four Gal>GalNAc-specific type-2 ribosome inactivating protein family lectins-ricin, abrin-a, Ricinus communis agglutinin 1, and Abrus precatorius agglutinin (APA), while the bovine ones reacted only with APA.General significanceThis study provides essential knowledge regarding the different roles of bioactive sites of lactoferrins in lectin–N-glycan recognition processes.

Research Highlights
► Recognition roles of N-glycans of lactoferrin (Lf) are examined with applied lectins. Both human and bovine Lf (hLf /bLf) react strongly with four Man- specific lectins. Native Lfs react well with Sambucus nigra agglutinin, a sialic acid specific lectin. However, hLf and bLf differ in binding intensity with Gal- specific lectins. These data indicate the recognition roles and glycotopes of N-glycans of hLf and bLf.