大肠杆菌志贺样毒素Ⅱ型基因的分子克隆

Cloning and nucleotide sequence of the gene for shiga-like toxin typeⅡfrom an Escherichia coli strain responsible for calf diarrhea

本文克隆了含大肠杆菌志贺样毒素Ⅱ型基因的2 0kbSau3AI酶切片断,对插入片段进行了核苷酸序列测定,1298bp的核苷酸序列包含2个完整的开放读框,其中SLTIIA亚基基因编码区长957bp,编码319个氨基酸多肽,SLTIIB亚基基因编码区长267bp,编码89个氨基酸多肽,与已知人源的SLTII基因核苷酸序列比较具有99%的同源性,与SLTI结构基因相比,A亚基同源序列为56 43%,B亚基为60 15%。

Genes of the shigalike toxin type Ⅱ in Escherichia coli of calf diarrhea were cloned from a plasmid library of total cellular DNA by screening recombinants with a DNA probe. Nucleotide sequence analysis was performed on 20 kb insert fragment which encoded the SLTⅡ gene. The nucleotide sequence data showed that the insert fragment contained two opening reading frames,in which the SLTⅡA and SLTⅡB coding sequences were 957 and 267 bp. Comparison of DNA sequences indicated that SLTⅡfrom calf origin shared 99?% homology with the DNA of the SLT Ⅱ from human origin,less homology with SLTⅠ.