title: Lactoferrin binding protein B - a bi-functional bacterial receptor protein.
abstract: Lactoferrin binding protein B (LbpB) is a bi-lobed outer membrane-bound lipoprotein that comprises part of the lactoferrin (Lf) receptor complex in Neisseria meningitidis and other Gram-negative pathogens. Recent studies have demonstrated that LbpB plays a role in protecting the bacteria from cationic antimicrobial peptides due to large regions rich in anionic residues in the C-terminal lobe. Relative to its homolog, transferrin-binding protein B (TbpB), there currently is little evidence for its role in iron acquisition and relatively little structural and biophysical information on its interaction with Lf. In this study, a combination of crosslinking and deuterium exchange coupled to mass spectrometry, information-driven computational docking, bio-layer interferometry, and site-directed mutagenesis was used to probe LbpB:hLf complexes. The formation of a 1:1 complex of iron-loaded Lf and LbpB involves an interaction between the Lf C-lobe and LbpB N-lobe, comparable to TbpB, consistent with a potential role in iron acquisition. The Lf N-lobe is also capable of binding to negatively charged regions of the LbpB C-lobe and possibly other sites such that a variety of higher order complexes are formed. Our results are consistent with LbpB serving dual roles focused primarily on iron acquisition when exposed to limited levels of iron-loaded Lf on the mucosal surface and effectively binding apo Lf when exposed to high levels at sites of inflammation.
authors.affiliation: Department of Microbiology & Infectious Diseases, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Nicholas K H
authors.initials: NK
authors.lastname: Ostan
authors.affiliation: Department of Microbiology & Infectious Diseases, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Rong-Hua
authors.initials: RH
authors.lastname: Yu
authors.affiliation: Department of Microbiology & Infectious Diseases, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Dixon
authors.initials: D
authors.lastname: Ng
authors.affiliation: Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Christine Chieh-Lin
authors.initials: CC
authors.lastname: Lai
authors.affiliation: Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Anastassia K
authors.identifier: 0000-0002-0228-1884
authors.initials: AK
authors.lastname: Pogoutse
authors.affiliation: Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Sarpe
authors.affiliation: Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Morgan
authors.identifier: 0000-0002-0611-4004
authors.initials: M
authors.lastname: Hepburn
authors.affiliation: Department of Chemistry, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Joey
authors.identifier: 0000-0002-9269-6863
authors.initials: J
authors.lastname: Sheff
authors.affiliation: Department of Chemistry, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Shaunak
authors.identifier: 0000-0003-3268-0621
authors.initials: S
authors.lastname: Raval
authors.affiliation: Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: David C
authors.initials: DC
authors.lastname: Schriemer
authors.affiliation: Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Trevor F
authors.identifier: 0000-0001-9883-6145
authors.initials: TF
authors.lastname: Moraes
authors.affiliation: Department of Microbiology & Infectious Diseases, University of Calgary, Calgary, Alberta, Canada.|Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Anthony B
authors.identifier: 0000-0002-4029-3296
authors.initials: AB
authors.lastname: Schryvers
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D007368:Interferometry; D007501:Iron / Q000378:metabolism; D013058:Mass Spectrometry; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D016297:Mutagenesis, Site-Directed; D009345:Neisseria meningitidis / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D033882:Transferrin-Binding Protein B / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D033882:Transferrin-Binding Protein B; C027768:lactoferrin binding proteins, bacterial; D007501:Iron