title: A lipopolysaccharide- and beta-1,3-glucan-binding protein from hemocytes of the freshwater crayfish Pacifastacus leniusculus. Purification, characterization, and cDNA cloning.
abstract: A lipopolysaccharide- and beta-1,3-glucan-binding protein (LGBP) was isolated and characterized from blood cells (hemocytes) of the freshwater crayfish Pacifastacus leniusculus. The LGBP was purified by chromatography on Blue-Sepharose and phenyl-Sepharose, followed by Sephacryl S-200. The LGBP has a molecular mass of 36 kDa and 40 kDa on 10% SDS-polyacrylamide gel electrophoresis under reducing and nonreducing conditions, respectively. The calculated mass of LGBP is 39,492 Da, which corresponds to the native size of LGBP; the estimated pI of the mature LGBP is 5.80. LGBP has binding activity to lipopolysaccharides as well as to beta-1,3-glucans such as laminarin and curdlan, but peptidoglycan could not bind to LGBP. Cloning and sequencing of LGBP showed significant homology with several putative Gram-negative bacteria-binding proteins and beta-1, 3-glucanases. Interestingly, LGBP also has a structure and functions similar to those of the coelomic cytolytic factor-1, a lipopolysaccharide- and glucan-binding protein from the earthworm Eisenia foetida. To evaluate the involvement of LGBP in the prophenoloxidase (proPO) activating system, a polyclonal antibody against LGBP was made and used for the inhibition of phenoloxidase (PO) activity triggered by the beta-1,3-glucan laminarin in the hemocyte lysate of crayfish. The PO activity was blocked completely by the anti-LGBP antibody. Moreover, the PO activity could be recovered by the addition of purified LGBP. These results suggest that the 36-kDa LGBP plays a role in the activation of the proPO activating system in crayfish and thus seems to play an important role in the innate immune system of crayfish.
authors.affiliation: Department of Comparative Physiology, Evolutionary Biology Center, Uppsala University, Norbyvägen 18A, S-75236, Uppsala, Sweden.
authors.forename: S Y
authors.initials: SY
authors.lastname: Lee
authors.forename: R
authors.initials: R
authors.lastname: Wang
authors.forename: K
authors.initials: K
authors.lastname: Söderhäll
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003400:Astacoidea / Q000235:genetics; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005618:Fresh Water; D005936:Glucans / Q000378:metabolism*; D006090:Gram-Negative Bacteria; D006434:Hemocytes / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D037102:Lectins; D008070:Lipopolysaccharides / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009835:Oligochaeta; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D002352:Carrier Proteins; D018076:DNA, Complementary; D005936:Glucans; C403975:LGBP protein, Pacifastacus leniusculus; D037102:Lectins; D008070:Lipopolysaccharides; D011994:Recombinant Proteins