cDNA cloning and expression of a collectin from red-spotted grouper (Epinephelus akaara)
- 海洋环境－已发表论文 
Lectins play a crucial role in the innate immunity of invertebrates and vertebrates by recognizing and disposing of pathogens. We obtained the complete cDNA of a C-type lectin (EALec1) from Epinephelus akaara using RACE. The complete EALec1 cDNA sequence was 827 bp. The 5-UTR and 3-UTR were 28 by and 151 bp, respectively, in length. The sequence also contained a polyadenylation signal AATAAA and a poly(A) tail. The EALec1 cDNA encodes polypeptides with 215 amino acids, including a signal peptide of 31 amino acids. The protein has a cysteine-rich region at the N terminal, a collagenous region characterized by G-X-Y repeats, a neck region, and a typical carbohydrate-recognition domain (CRD), indicating that EALec1 is a collectin. The key recognition positions of this CRD are EPD, isolated for the first time in fish. These are likely the interim types, between mannan-binding lectin and galactose-binding lectin. We evaluated the expression pattern of EALec1 in 12 different tissues using RT-PCR. EALec1 was expressed in all tissues, though at different levels. In addition, we inserted EALec1 into an expression vector (pET-28a) for transformation into the BL21 engineering bacteria. Based on enzyme digestion and sequencing of the positive clone, we successfully constructed the EALec1 recombinant expression vector.