A new C-type lectin (FcLec5) from the Chinese white shrimp Fenneropenaeus chinensis.
C-type lectins are one family of pattern recognition receptors (PRRs) that play important roles in innate immunity. In this work, cDNA and genomic sequences for a new C-type lectin (FcLec5) were obtained from the Chinese white shrimp Fenneropenaeus chinensis. FcLec5 cDNA contains an open reading frame of 1,008 bp and its genomic sequence is 1,137 bp with 4 exons and 3 introns. The predicted FcLec5 protein contains a signal peptide and two carbohydrate recognition domains (CRDs). The N-terminal CRD of FcLec5 has a predicted carbohydrate recognition motif of Gln-Pro-Asp (QPD), while the C-terminal CRD contains a motif of Glu-Pro-Gln (EPQ). Northern blot analysis showed that FcLec5 mRNA was specifically expressed in hepatopancreas. FcLec5 protein was expressed in hepatopancreas and secreted into hemolymph. Real-time PCR showed that FcLec5 transcript exhibited different expression profiles after immune-challenged with Vibrio anguillarum or White Spot Syndrome Virus (WSSV). Recombinant FcLec5 and its two individual CRDs could agglutinate most bacteria tested, and the agglutinating activity was Ca2+-dependent. Besides, the agglutinating activity to gram-negative bacteria is higher than that to gram-positive bacteria. Direct binding assay showed that recombinant FcLec5 could bind to all microorganisms tested (five gram-positive and four gram-negative bacteria, as well as yeast) in a Ca2+-independent manner. Recombinant FcLec5 also directly bound to bacterial peptidoglycan, lipopolysaccharide and lipoteichoic acids. These results suggest that FcLec5 may act as a PRR for bacteria via binding to bacterial cell wall polysaccharides in Chinese white shrimp.
Xu
Wen-Teng
WT
School of Life Sciences, Shandong University, Jinan, 250100, Shandong, China.
Wang
Xian-Wei
XW
Zhang
Xiao-Wen
XW
Zhao
Xiao-Fan
XF
Yu
Xiao-Qiang
XQ
Wang
Jin-Xing
JX
D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D037181:Lectins, C-Type / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D008969:Molecular Sequence Data; D033561:Penaeidae / Q000235:genetics* / Q000382:microbiology; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D018076:DNA, Complementary; D037181:Lectins, C-Type; D012333:RNA, Messenger; D011994:Recombinant Proteins