Gene Cloning, Expression And Structure-Function Study Of Toxins From The Chinese Bird Spiders

The spider Ornithoctonus huwena (Wang) [=Selenocosmia huwena Wang] is distributed in the hilly areas of Guangxi and Yunnan in the south of China. In previous work, many components with different structures and functions were purified and characterized. The nine cDNA sequences of the huwena toxin were cloned and sequenced, It was classified into three different superfamilies according to the prepro region of cDNA sequences. In this study, the cDNA encoding HWTX-Vwas cloned and sequenced by RACE, classified into the three superfamilies. On the basis of their amino acid sequences, we designed and synthesized 3' RACE and 5' RACE primers. By overlapping the two partial cDNA sequences obtained by 3' and 5' RACE, the full-length sequence was obtained. The full length cDNA of HWTX-V contain 459 bases composed of 5' UTR, ORF, 3' UTR. Compared with the other cDNAs and the prepro regions of the huwena(HWTX- I, II, III, IV, VII), it was demonstrated high similarity to the HWTX- I, III, IV, but was not similarity to the HWTX-II, VII Thus, the HWTX-V shares the same superfamily. The pairing model of three disulfide bonds is Cys(I-TV), Cys(II-V), Cys(III-VI), the key structure composes of a triple-stranded antiparallel P-sheet and a disulfide knot, which is the characteristic property of ICK motif. The open reading frame encoded a precursor protein of 86 residues, including a signal peptide and prepro region of 50 residues and a mature peptide of 35 residues, an additional residue Lys was found at the C terminus of the mature peptide before the stop codon.The spider Chilobrachis jingzhao is distributed in the hilly areas of Hainan in China. In previous work, about 20 toxins was sequence and characterized. Five cDNAs encode JZTX-I, JZTX-III, JZTX-VI, JZTX-VII, JZTX-IX were cloned and sequenced. All the five cDNAs composed of 5'UTR, open reading frame (OFR) and 3'UTR. The OFR encode a precursor including a potential signal peptide of 20 to 23 residues, a mature toxin of about 30 residues and an intervening pro region. The length of the five toxins prepro regions varied from less than 10 to over 30 residues, further more, there have low similarity to these...