title: A novel myeloid differentiation factor 88 homolog, SpMyD88, exhibiting SpToll-binding activity in the mud crab Scylla paramamosain.
abstract: Myeloid differentiation factor 88 (MyD88) is an essential regulator in the Toll or Toll-like receptor (TLR) signaling pathway. In the current study, we characterized a novel crustacean MyD88 homolog, SpMyD88, and analyzed its binding activity with SpToll. The full-length cDNA sequence of SpMyD88 is 2933 bp, with a 1419 bp open reading frame encoding a 472-amino acid protein. No signal peptide was predicted. A death domain (residues 19-103), a Toll/interleukin-1 receptor (TIR) domain (residues 156-297), and a C-terminal extension (CTE) domain (residues 298-472) were also found. In a phylogenetic tree constructed with MyD88 homologs from both invertebrates and vertebrates, arthropod MyD88s including SpMyD88 formed a cluster containing a unique CTE domain. SpToll shared the highest identity with human TLR4. These two receptors were grouped into a cluster of a tree constructed based on the conserved TIR domains. SpToll also had a close relationship with other shrimp TLRs that possess potential antibacterial activity. SpMyD88 was highly expressed in the hemocytes, gills, hepatopancreas, and eye stalks. Upon challenge with Vibrio harveyi, both SpMyD88 and SpToll were significantly increased in the hemocytes, whereas only SpMyD88 was elevated by Staphylococcus aureus. In addition, a pull-down assay demonstrated that SpMyD88 showed a binding activity with SpToll. These results suggest that SpMyD88 and SpToll are involved in the defense system of mud crabs against Gram-negative bacteria.
authors.affiliation: East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of East China Sea and Oceanic Fishery Resources Exploitation, Ministry of Agriculture, Shanghai 200090, China. lixin8687@163.com
authors.forename: Xin-Cang
authors.initials: XC
authors.lastname: Li
authors.forename: Lei
authors.initials: L
authors.lastname: Zhu
authors.forename: Lin-Gui
authors.initials: LG
authors.lastname: Li
authors.forename: Qian
authors.initials: Q
authors.lastname: Ren
authors.forename: Yan-Qing
authors.initials: YQ
authors.lastname: Huang
authors.forename: Jian-Xue
authors.initials: JX
authors.lastname: Lu
authors.forename: Wen-Hong
authors.initials: WH
authors.lastname: Fang
authors.forename: Wei
authors.initials: W
authors.lastname: Kang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D003386:Brachyura / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D018076:DNA, Complementary; D020869:Gene Expression Profiling; D007375:Interleukin-1 / Q000378:metabolism; D008969:Molecular Sequence Data; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017422:Sequence Analysis, DNA; D013211:Staphylococcus aureus / Q000472:pathogenicity; D014018:Tissue Distribution; D051193:Toll-Like Receptors / Q000378:metabolism*; D014733:Vibrio / Q000472:pathogenicity
chemical_list: D023181:Antimicrobial Cationic Peptides; D018076:DNA, Complementary; D007375:Interleukin-1; D053594:Myeloid Differentiation Factor 88; D051193:Toll-Like Receptors