不同地区幽门螺杆菌cagA基因羧基端可变区及其蛋白序列差异分析  

Diversity of cagA gene 3' terminal variable region and its corresponding protein in Helicobacter pylori

作　　者：吴莺[1] 张尤历[1] 王文兵[2] 陈劲频[1] 沈琰[1] 

机构地区：[1]江苏大学附属医院消化科,江苏省镇江市212001 [2]江苏大学生命科学院,江苏省镇江市212001

出　　处：《世界华人消化杂志》2007年第7期746-749,共4页World Chinese Journal of Digestology

基　　金：江苏省科学技术厅社会发展项目;No.BS2002023~~

摘　　要：目的:比较不同地区H pylori cagA 3'端可变区序列差异及序列的地域特征,分析差异与疾病的相关性.方法:选择本实验室所收集的20例cagA+的PCR产物进行测序,并通过ExPASy-Translation软件推测其氨基酸序列,搜索并收集GenBank中已公布的不同地区3-6个H pyloricagA 3'端可变区序列及其氨基酸序列进行比较分析.结果:cagA蛋白的氨基酸序列可分为具有明显地域特征的东亚型和西方型两类;部分东亚型菌株表现出西方型变异.87.4%的菌株具有3个串联排列的EPIYA基序,8.2%的菌株具有4个或以上EPIYA基序.新发现1条具有区域特征的含有3个氨基酸的序列.cagA蛋白氨基酸序列中的EPIYA数目与临床结果没有相关性.结论:H pylori cagA基因及其cagA蛋白序列具有明显多态性,可以根据H pylori cagA 3'端可变区的主要序列差异进行地域分型,cagA 3'端可变区的EPIYA基序的数目与临床结果没有相关性.AIM： To study the diversity and structural characteristics of cagA （cytotoxin-associated gene A） gene 3＇ terminal variable region in Helicobacter pylori as well as their correlations with the outcome of H pylori-related diseases. METHODS： PCR products with positive H pylori cagA were obtained from 20 cases and then sequenced by ExPASy-Translation software. Meanwhile, 3 to 6 cases of H pylori 3＇ terminal variable region and amino acid sequence, collected from NCBI database in different countries, were comparatively analyzed. RESULTS： The amino acid sequences were found with obvious regional characteristics,and could be classified into eastern-asian type and western type. Western-type aberrations occurred in some eastern-asian strains. Totally, 87.4% H pylori stains contained 3 EPIYA motifs in series, and 8.2% strains had 4 or more EPIYA motifs. A new sequence containing 3 amino acids was found. There was no correlation between the numbers of EPIYA motifs in the amino acid sequences of cagA protein and the clinical outcomes. CONCLUSION： There exists marked diversity in cagA gene and protein of H pylori, which can be distinguished by the main sequences of H pylori cagA 3＇ terminal variable region. The number of EPIYA motifs in cagA 3＇ terminal variable region is not correlated with the clinical outcomes of diseases.

关 键 词：幽门螺杆菌 细胞毒性相关基因A EPIYA基序 差异 

分 类 号：R378[医药卫生—病原生物学]