Bacterial lactoferrin-binding protein B (LbpB)

Bacterial lactoferrin-binding protein B (LbpB) is a **bi-lobed lipoprotein receptor** located on the outer membrane of pathogenic Gram-negative bacteria such as *Neisseria meningitidis*, *Neisseria gonorrhoeae*, and several *Moraxella* species[1][3][5][9]. LbpB is a component of the **lactoferrin receptor complex** and has two major biological roles: - **Iron acquisition**: LbpB binds specifically to iron-loaded (holo-) lactoferrin (Lf), an iron-carrying protein found in host secretions, capturing iron for bacterial use. The N-lobe of LbpB interacts extensively with the C-lobe of human lactoferrin[1][2][3][5][7]. It mediates the delivery of iron to an associated membrane transporter (LbpA), facilitating iron piracy - an essential process for bacterial survival and pathogenicity in iron-limited host environments[1][2][3][7]. - **Immune evasion**: The C-terminal lobe of LbpB contains anionic amino acid stretches that can sequester cationic antimicrobial peptides (e.g., lactoferricin, a potent fragment generated from lactoferrin digestion), thus protecting bacteria from host immune defenses[1][2][5][7][9]. This receptor, therefore, represents a potential **therapeutic target** and a **vaccine candidate** for preventing or treating infections by these pathogens—although structural variation between strains poses challenges[2][5][7]. No small-molecule or approved biologic drugs are known to directly target LbpB. Structural studies indicate that LbpB's interaction with lactoferrin is highly specific for the iron-bound form and that both its N- and C-lobes contribute to its dual functions[1][2][3][5][7][9]. LbpB is transported to and anchored in the bacterial outer membrane via lipidation at its N-terminus[2]. In summary, LbpB is a **bacterial outer membrane receptor** essential for iron acquisition and defense against host innate immunity in several Gram-negative pathogens, playing a critical role in bacterial virulence during infection.[1][2][5][7][9]

Other names

Lactoferrin binding protein BLbpBNeisserial lactoferrin-binding protein B

Inhibition by antibodies (prospective, not an approved therapeutic mechanism)