Primary structure and characteristics of a lectin from skin mucus of the Japanese eel Anguilla japonica.
Two types of lactose-binding lectins, AJL-1 and AJL-2, were purified from the skin mucus extract of the Japanese eel Anguilla japonica by lactose affinity chromatography and subsequent gel filtration. The molecular masses of AJL-1 and AJL-2 were 16,091 and 31,743 Da, respectively. Intact AJL-1 was comprised of two identical 16-kDa subunits having blocked N termini and no disulfide bonds. AJL-2 was a homodimer with disulfide bonds. Based on the N-terminal amino acid sequence of the AJL-2 monomer, the nucleotide sequence of cDNA encoding this lectin was determined by 3'- and 5'-rapid amplification of cDNA ends. The deduced amino acid sequence showed approximately 30% homology with C-type lectins, which bind to carbohydrates in a Ca(2+)-dependent manner. In addition, AJL-2 exhibited highly conserved consensus amino acid residues of the C-type carbohydrate recognition domain, although this lectin showed Ca(2+)-independent activity. Gene expression of AJL-2 was detected only in the skin by Northern blot analysis, and this lectin localization was demonstrated in the club cells by immunohistochemistry. These results indicate that AJL-2 is secreted on the body surface and function as a component of skin mucus. AJL-2 agglutinated Escherichia coli and suppressed its growth, suggesting that this lectin is involved in host defense.
Tasumi
Satoshi
S
Fisheries Laboratory, The University of Tokyo, Shizuoka 431-0211, Japan.
Ohira
Tsuyoshi
T
Kawazoe
Ichiro
I
Suetake
Hiroaki
H
Suzuki
Yuzuru
Y
Aida
Katsumi
K
D000595:Amino Acid Sequence; D000811:Anguilla; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D050260:Carbohydrate Metabolism; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D019281:Dimerization; D004912:Erythrocytes / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D015870:Gene Expression; D006384:Hemagglutination; D007150:Immunohistochemistry; D037102:Lectins / Q000737:chemistry* / Q000235:genetics* / Q000494:pharmacology; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D012867:Skin / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014018:Tissue Distribution
D018076:DNA, Complementary; D037102:Lectins; D012313:RNA