摘要
目的克隆幽门螺杆菌中国株MEL-Hp 27cagA全长基因,并进行分子特征分析。方法参考Hp26695基因组序列,分别针对cagA基因编码区保守序列和位于cagA基因上、下游的基因序列设计两对PCR引物,交叉分段扩增包括cagA基因编码区、5′、3′非编码区在内的全长基因序列,并对cagA基因调控序列、编码序列及源自中国的CagA分子EPIYA基序分布特点进行分析。结果Hp27cagA基因编码区长3510bp,编码1169个氨基酸。5′端非编码区长649bp,-10区、-35区分别位于起始密码子ATG上游89bp和154bp处,3′端非编码区长476bp。Hp27cagA基因编码区核苷酸序列与东亚菌株同源性为96%,与西方菌株的同源性仅为86%左右。Hp27CagA分子存在典型的EPIYA基序,属于ABD型,与国际参考株NCTC11637的AB-CCC型不同。比较源自中国的HpCagA序列的EPIYA基序分布特点,未发现中国Hp分离株之间存在CagAEPIYA基序与疾病结局(胃癌、慢性胃炎和十二指肠溃疡)的聚类关系。结论成功克隆幽门螺杆菌全长ca-gA基因;cagA基因编码区及非编码区序列存在东西方差异;未发现中国Hp分离株之间存在CagA EPIYA基序与疾病结局的聚类关系。
To clone the full length cagA gene of Helicobacter pylori MEL-Hp27 isolated in China and to analyze its molecular characteristics, two pairs of primers were designed according to the nucleic acid sequences of the conserved fragment in the coding region of cagA gene and the sequences located in the up-stream or down-stream of the cagA gene using a PCR-based approach, full length MEL-Hp27 cagA gene with its 5＇ and 3＇ non-coding regions （UTR） was then cloned, and the homology of the cagA gene sequence, the regulatory sequence and the distribution of the 5-amino acid motifs EPIYA of CagA protein were analyzed. In this way, the cagA gene of 3510 bp with 5＇ UTR of 649 bp and 3＇ UTR of 476 bp encoding 1169 amino acids was cloned. The --10 box and --30 box were located in the up-stream of cagA gene, and their distances from ATG were 89 bp and 154 bp respectively. Sequence analysis showed that the coding region of cagA gene of MEL-Hp27 shared 96 % and 86 % of homology with H. pylori Far East strains and Western strains respectively. There was also heterogeneity in the un-translated region of cagA between Far East and Western strain of H. pylori. In addition, the tyrosine phosphrylation motif （EPIYA-ABD） was present in CagA protein of MEL-Hp27, which was different from the motif AB-CCC of the international reference strain NCTCl1637, however, there was no significant difference in the EPIYA motif among different isolates of H. pylori from patients with different diseases in China.
出处
《中国人兽共患病学报》
CAS
CSCD
北大核心
2007年第5期484-488,共5页
Chinese Journal of Zoonoses
基金
河南省医学创新人才基金资助项目(2000-84)
