Characterization of defensin gene from abalone Haliotis discus hannai and its deduced protein

Defensin is one of preserved ancient host defensive materials formed in biological evolution. As a regulator and effector molecule, it is very important in animals＇ acquired immune system. This paper reports the defensin gene from the mixed liver and kidney cDNA library of abalone Haliotis discus hannai Ino. Sequence analysis shows that the gene sequence of full-length cDNA encodes 42 mature peptides （including six Cys）, molecular weight of 4 323 Da, and pI of 8.02. Amino acid sequence homology analysis shows that the peptides are highly similar （70% in common） to other insects defensin. Because of a typical insect-defensin structural character of mature peptide in the secondary structure, the polypeptide named Haliotis discus defensin （hd-def）, a novel of antimicrobial peptides, belongs to insects defensin subfamily. The RT-PCR result of Haliotis discus defensin shows that the gene can be expressed only in the hepatopancreas by Gram-negative and positive bacteria stimulation, which is ascribed to inducible expression. Therefore, it is revealed that the Haliotis discus defensin gene expression was related to the antibacterial infection of Haliotis discus hannai Ino.

Defensin 是防御材料在生物进化形成了的保存古老的主人之一。作为一个管理者和受动器分子，它在动物的家是很重要的获得的免疫系统。这篇论文从混合的肝和鲍鱼 Haliotis 铁饼 hannai Ino 的肾 cDNA 图书馆报导 defensin 基因。顺序分析证明全身的 cDNA 的基因顺序编码 42 成熟的肽(包括六 Cys ) ， 4 323 Da 的分子的重量，和 8.02 的 pI。氨基酸顺序相同分析证明肽是高度类似的(70% 在里面普通) 到另外的昆虫 defensin。因为典型 insect-defensin 在第二等的结构的成熟的肽的结构的特性，多肽把 Haliotis 称为铁饼 defensin (hd-def ) ，抗菌剂肽的一篇小说，属于昆虫 defensin 亚科。Haliotis 铁饼 defensin 的 RT-PCR 结果证明基因能被克否定、积极的细菌刺激仅仅在 hepatopancreas 表示，它被归功于到可诱导的表示。因此， Haliotis 铁饼 defensin 基因表示与 Haliotis 铁饼 hannai Ino 的抗菌剂感染有关，这被揭示。