Construction of Recombinant Chimeric Human Lactoferrin/Bovine Transferrins

Abstract

One of the contributing factors to bacterial pathogenesis is the ability to acquire iron (Fe) in the extremely Fe scarce environment of the host. The families Neisseriaceae and Pasteurellaceae, which include a number of human and veterinary pathogens, express outer membrane receptors that specifically bind and remove Fe from the hosts’ Fe binding proteins, transferrin (Tf) and lactoferrin (Lf)⁵. The bacterial Lf receptor was initially identified by affinity methods with immobilized human Lf (hLf) as the affinity matrix, using high salt and pH conditions to minimize nonspecific interactions¹¹. These studies identified a single Fe-repressible outer membrane protein, lactoferrin binding protein (Lbp), in constrast to the two transferrin binding proteins, transferrin binding protein A (TbpA) and transferrin binding protein B (TbpB), that were isolated with a Tf affinity column¹¹. Lbp shared several properties with TbpA and once the gene encoding Lbp was cloned⁹ it was apparent that the predicted protein sequence was homologous to TbpA.