The lactoferrin receptor complex in gram negative bacteria

Abstract

Bacteria that inhabit the respiratory and genitourinary tracts of mammals encounter an iron-deficient environment on the mucosal surface where iron is complexed by the host iron-binding proteins transferrin and lactoferrin. Lactoferrin is also present in high concentrations at sites of inflammation where the cationic anti-microbial peptide lactoferricin is produced by proteolysis of lactoferrin. Several members of the Neisseriaceae and Moraxellaceae families express surface receptors, capable of specifically binding host lactoferrin and extracting the iron from lactoferrin as a source of iron for growth. The receptor is comprised of an integral outer membrane protein, lactoferrin binding protein A (LbpA), and a largely exposed surface lipoprotein, lactoferrin binding protein B (LbpB). LbpA is essential for mediating growth using lactoferrin as a sole iron source whereas LbpB only plays a facilitating role. LbpB, with the presence of a large tract of negatively charged residues, appears to protect the bacterial cell from the bactericidal effects of the lactoferricin. The lactoferrin receptors in these species appear to be essential for survival and thus may serve as potential vaccine targets.

Genomic Characterization of the Taylorella Genus

“…We also identified among the T. equigenitalis -specific CDSs randomly inserted into the genome, virulence-associated genes for TonB-dependent lactoferrin and transferrin receptors (TEQUI_0057, TEQUI_0058, TEQUI_0902 and TEQUI_0903) and for the Heat shock protein 60 (Hsp60: TEQUI_0973). TonB-dependent outer membrane receptors for lactoferrin or transferrin are identified as allowing iron to be imported from the mammalian iron carriers lactoferrin and transferrin across the outer membrane [63]. Iron being essential for microbial growth, the ability to acquire ferric iron from the host is directly related to virulence, which suggests that the more virulent character of T. equigenitalis could be due to a better iron acquisition capacity than T. asinigenitalis .…”

Interdependence between iron acquisition and biofilm formation in Pseudomonas aeruginosa

“…First, some pathogens express receptors for lactoferrin or transferrin, in a bid to acquire the proteins and their associated iron (Beddek and Schryvers, 2010; Pogoutse and Moraes, 2017). Second, many human pathogens have heme acquisition pathways comprised of heme-binding receptors and/or even heme-binding molecules called hemophores (Cescau et al ., 2007; Huang and Wilks, 2017).…”

Resistance and survival strategies of Salmonella enterica to environmental stresses

“…For example, Neisseria and Moraxella species produce transferrin and lactoferrin receptors allowing for the direct uptake of bound iron from these proteins (Beddek & Schryvers, 2010). Other Gram-negative bacteria such as Serratia marcescens, Pseudomonas aeruginosa, and Haemophilus influenzae express receptors for the uptake of heme, hemoproteins, or hemophores (Cope et al, 1995;Ghigo et al, 1997;Lettofe et al, 1998).…”