Analysis of the Alpha-Toxin Gene of Clostridium Perfringens

(1) α -毒素基因的核苷酸序列表明，毒素由398个氨基酸组成，其中n端信号序列为28个氨基酸。亲水特征表明底物结合域位于n端附近。(2)基因文库中α -毒素克隆的高发生率可能表明染色体中存在大量的毒素基因拷贝。然而，对插入到60个克隆中的DNA片段的分析以及用特定探针对染色体DNA的杂交表明，α -毒素基因是作为单个基因出现的。(3) 0.6 kb上游区域的核苷酸序列显示，在启动子上游存在两个独特的核苷酸序列。缺失分析表明其中一个序列特征弯曲DNA可能参与了基因表达的调控。

(1) Nucleotide sequence of the alpha-toxin gene showed that the toxin consisted of 398 amino acids with a N-terminal signal sequence of 28 amino acids. A hydropathy profile suggests that a substrate binding domain is located close to N-terminal.(2) High incidence of alpha-toxin clone in the gene library may imply that a large number copies of the toxin genes exist in a chromosome. However, analysis of DNA fragment inserted to 60 clones and hybridization of chromosome DNA with a specific probe indicate the alpha-toxin gene occurs as a single gene.(3) Nucleotide sequence of a 0.6 kb upstream region showed the presence of two unique nucleotide sequence immediately upstream of the promoter. Deletion analysis indicates that one of them, sequence characteristic bent DNA could be involved in the regulation of the gene expression.