title: LBP/BPI proteins and their relatives: conservation over evolution and roles in mutualism.
abstract: LBP [LPS (lipopolysaccharide)-binding protein] and BPI (bactericidal/permeability-increasing protein) are components of the immune system that have been principally studied in mammals for their involvement in defence against bacterial pathogens. These proteins share a basic architecture and residues involved in LPS binding. Putative orthologues, i.e. proteins encoded by similar genes that diverged from a common ancestor, have been found in a number of non-mammalian vertebrate species and several non-vertebrates. Similar to other aspects of immunity, such as the activity of Toll-like receptors and NOD (nucleotide-binding oligomerization domain) proteins, analysis of the conservation of LBPs and BPIs in the invertebrates promises to provide insight into features essential to the form and function of these molecules. This review considers state-of-the-art knowledge in the diversity of the LBP/BPI proteins across the eukaryotes and also considers their role in mutualistic symbioses. Recent studies of the LBPs and BPIs in an invertebrate model of beneficial associations, the Hawaiian bobtail squid Euprymna scolopes' alliance with the marine luminous bacterium Vibrio fischeri, are discussed as an example of the use of non-vertebrate models for the study of LBPs and BPIs.
authors.affiliation: Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, 1550 Linden Drive, Madison, WI 53562, USA.
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Krasity
authors.forename: Joshua V
authors.initials: JV
authors.lastname: Troll
authors.forename: Jerrold P
authors.initials: JP
authors.lastname: Weiss
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: McFall-Ngai
mesh_terms: D000209:Acute-Phase Proteins / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000235:genetics* / Q000378:metabolism; D001798:Blood Proteins / Q000235:genetics* / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D017124:Conserved Sequence; D019143:Evolution, Molecular; D006801:Humans; D050356:Lipid Metabolism; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D008954:Models, Biological; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid; D013559:Symbiosis / Q000502:physiology; D000099231:Lipopolysaccharide-Binding Protein
chemical_list: D000209:Acute-Phase Proteins; D023181:Antimicrobial Cationic Peptides; D001798:Blood Proteins; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D000099231:Lipopolysaccharide-Binding Protein; C021623:bactericidal permeability increasing protein