A novel 40-kDa protein containing six repeats of an epidermal growth factor-like domain functions as a pattern recognition protein for lipopolysaccharide.
Determination of structures and functions of pattern recognition proteins are important for understanding pathogen recognition mechanisms in host defense and for elucidating the activation mechanism of innate immune reactions. In this study, a novel 40-kDa protein, named LPS recognition protein (LRP), was purified to homogeneity from the cell-free plasma of larvae of the large beetle, Holotrichia diomphalia. LRP exhibited agglutinating activities on Escherichia coli, but not on Staphylococcus aureus and Candida albicans. This E. coli-agglutinating activity was preferentially inhibited by the rough-type LPS with a complete core oligosaccharide. LRP consists of 317 aa residues and six repeats of an epidermal growth factor-like domain. Recombinant LRP expressed in a baculovirus system also showed E. coli agglutination activity in vitro and was able to neutralize LPS by inhibition of LPS-induced IL-6 production in mouse bone marrow mast cells. Furthermore, E. coli coated with the purified LRP were more rapidly cleared in the Holotrichia larvae than only E. coli, indicating that this protein participates in the clearance of E. coli in vivo. The three amino-terminal epidermal growth factor-like domains of LRP, but not the three carboxyl epidermal growth factor-like domains, are involved in the LPS-binding activity. Taken together, this LRP functions as a pattern recognition protein for LPS and plays a role as an innate immune protein.
Ju
Jin Sung
JS
National Research Laboratory of Defense Proteins, College of Pharmacy and Research Institute for Drug Development, Pusan National University, Busan, Korea.
Cho
Mi Hyang
MH
Brade
Lore
L
Kim
Jung Hyun
JH
Park
Ji Won
JW
Ha
Nam-Chul
NC
Söderhäll
Irene
I
Söderhäll
Kenneth
K
Brade
Helmut
H
Lee
Bok Luel
BL
D000371:Agglutination; D000595:Amino Acid Sequence; D000818:Animals; D002474:Cell-Free System / Q000737:chemistry / Q000276:immunology / Q000382:microbiology; D001517:Coleoptera / Q000276:immunology / Q000382:microbiology; D004815:Epidermal Growth Factor / Q000737:chemistry*; D004926:Escherichia coli / Q000276:immunology; D006458:Hemolymph / Q000737:chemistry / Q000276:immunology / Q000382:microbiology; D019476:Insect Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D007814:Larva / Q000276:immunology / Q000382:microbiology; D018950:Lipopolysaccharide Receptors / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D008070:Lipopolysaccharides / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017434:Protein Structure, Tertiary; D051192:Receptors, Pattern Recognition / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D020449:Repetitive Sequences, Amino Acid
D019476:Insect Proteins; C512919:LRP protein, Holotrichia diomphalia; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D051192:Receptors, Pattern Recognition; D004815:Epidermal Growth Factor