title: Purification, characterization and cDNA cloning of a novel lipopolysaccharide-binding lectin from the shrimp Penaeus monodon.
abstract: In invertebrates, C-type lectin plays an important role in innate immunity by mediating the recognition of pathogens to host cells and clearing microinvaders. A few C-type lectins have been identified from shrimps, but none of their gene or protein sequences is known to date. In this paper, a C-type lectin (named PmLec) specific for bacterial lipopolysaccharide was purified from the serum of the shrimp Penaeus monodon. The binding of PmLec to lipopolysaccharide was mainly mediated through the O-antigen. PmLec had a strong hemagglutinating and bacterial-agglutinating activity as well as an opsonic effect that enhances hemocyte phagocytosis. The PmLec cDNA sequence was obtained from the cDNA library of P. monodon by polymerase chain reaction with the degenerated primer designed according to the amino-terminal residue sequence of purified PmLec. A 546-bp open reading frame was found to encode a putative protein comprising 182 amino acids and containing a preceding signal peptide of 17 amino acids. A C-type lectin domain existed in PmLec, but no glycosylation site was found. The recombinant PmLec protein expressed in Escherichia coli also showed the same agglutinating activity and opsonic effect as that of the native protein. This is the first report of a lectin cDNA from the shrimp. PmLec functions as a pattern-recognition protein and an opsonin in the shrimp, and it provides a clue to elucidate the role of lectin in the innate immunity of aquatic invertebrates at the molecular level.
authors.affiliation: Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration (SOA), Xiamen 361005, People's Republic of China.
authors.forename: Tian
authors.initials: T
authors.lastname: Luo
authors.forename: Haijie
authors.initials: H
authors.lastname: Yang
authors.forename: Fang
authors.initials: F
authors.lastname: Li
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Zhang
authors.forename: Xun
authors.initials: X
authors.lastname: Xu
mesh_terms: D000818:Animals; D003001:Cloning, Molecular / Q000379:methods; D018076:DNA, Complementary / Q000235:genetics; D007113:Immunity, Innate / Q000235:genetics*; D037181:Lectins, C-Type / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D008562:Membrane Glycoproteins; D008969:Molecular Sequence Data; D033561:Penaeidae / Q000235:genetics / Q000276:immunology*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D018076:DNA, Complementary; D037181:Lectins, C-Type; D008562:Membrane Glycoproteins