title: Biochemical analysis of lactoferrin receptors in the Neisseriaceae: identification of a second bacterial lactoferrin receptor protein.
abstract: Bacterial transferrin receptors that have been described in the families Pasteurellaceae and Neisseriaceae are composed of two receptor proteins, transferrin binding proteins 1 and 2 (Tbp1 and Tbp2). In contrast, bacterial lactoferrin receptors have only been described for human pathogens in the family Neisseriaceae, and were believed to consist of a single protein, Lbp1, which is highly homologous to Tbp1. We describe a modified affinity isolation procedure that facilities isolation of a second lactoferrin receptor protein Lbp2 (a presumptive Tbp2 homologue) from Neisseria meningitidis, Moraxella catarrhalis and Moraxella bovis using immobilized lactoferrin. Antiserum specific for either the M. catarrhalis Tbp1+2 molecules, the M. catarrhalis Lbp1 molecule, or for a commercial preparation of human lactoferrin did not react on western blots with the same organisms' affinity purified Lbp2. In addition, the M. catarrhalis Lbp2 could be isolated in a functional form without contaminating Lbp1 or Tbp1+2. We also demonstrate that the bovine pathogen, M. bovis, produces functional transferrin and lactoferrin receptors specific for the bovine forms of these glycoproteins. A putative lbpB gene, recently speculated to reside immediately upstream of the N. meningitidis Lbp1 structural gene, lbpA, likely encodes the newly isolated Lbp2 protein from this bacterial species.
authors.affiliation: Department of Microbiology and Infectious Diseases, University of Calgary, Alberta, Canada.
authors.forename: R A
authors.initials: RA
authors.lastname: Bonnah
authors.forename: R
authors.initials: R
authors.lastname: Yu
authors.forename: A B
authors.initials: AB
authors.lastname: Schryvers
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D033862:Iron-Binding Proteins; D016955:Moraxella bovis / Q000737:chemistry*; D001936:Moraxella catarrhalis / Q000737:chemistry; D009345:Neisseria meningitidis / Q000737:chemistry; D009346:Neisseriaceae / Q000737:chemistry*; D011817:Rabbits; D011956:Receptors, Cell Surface / Q000737:chemistry*; D011990:Receptors, Transferrin / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate; D033863:Transferrin-Binding Proteins
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D033862:Iron-Binding Proteins; D011956:Receptors, Cell Surface; D011990:Receptors, Transferrin; D033863:Transferrin-Binding Proteins; C038340:lactoferrin receptors; D012967:Sodium Dodecyl Sulfate