【摘要】 目的 :伤寒沙门菌 2 75主动外排系统acrAB全基因测序并分析其结构。方法 :以伤寒沙门菌基因序列为参考设计引物 ,以PCR法对伤寒沙门菌 2 75acrAB全序列进行调取并测序。结果 :伤寒沙门菌 2 75acrAB全序列与参考伤寒沙门菌 (No .AL6 2 72 6 7)同源性 99.38% ,与大肠杆菌 (No .U0 0 734)同源性 84 .6 9%。伤寒沙门菌 2 75acrR正向编码 2 17个氨基酸 ,acrA反向编码 397个氨基酸 ,acrB反向编码 10 4 9个氨基酸 ,同参考伤寒沙门菌比较 ,acrR相同 ,acrA、acrB各一处不同 ;与大肠杆菌比较 ,同源性分别为 86 .98%、91.6 9%、94 .6 6 %。acrA、acrR启动区位于 4 36 7～ 4 5 0 7碱基处 ,SD序列 (RBS)位于 4 373～ 4 377碱基处。acrA与acrB间隔区位于 315 1～ 3172碱基处 ,SD序列 (RBS)位于 316 1～ 316 5碱基处。结论 :伤寒沙门菌acrAB主动外排系统在结构、碱基序列和编码的氨基酸序列上均与大肠杆菌有很高的同源性 ,它可能是伤寒沙门菌引起多重耐药的主要原因。更多还原

【Abstract】 Objective:To identify the sequence of the multiple-antibiotic-resistant efflux acrAB gene in Salmonella typhi 275(a clinically isolated strain) and analyze its structure,amino acid sequence.Methods:The whole acrAB gene of Salmonella typhi 275 were amplified by PCR with the primers designed from Genebank,and the sequence of products and the amino acid sequence were detected.Results:The whole sequence of acrAB gene of Salmonella typhi 275 contained 5156 bases and 99.38% identity were found in comparison with the reference sequence of Salmonella typhi (Genebank No. AL627267);84.69% identity were detected in comparison with that of Escherichia coli (Genebank No.ECUO0734).The acrR,actA,acrB of Salmonella typhi 275 coded AcrR,AcrA,AcrB proteins with 217,397 and 1049 amino acids,respectively.1 amino acid alteration existed in both AcrA (Ser270Thr)and AcrB (Met964Thr) in comparison with the reference Genebank amino acids sequence.Compared with Escherichia coli,28,33 and 56 amino acids alteration and 86.98%,91.69% and 94.66% identity in the AcrR,Acta and AcrB were found respectively.2 additional amino acids existed in AcrR of Salmonella typhi 275.The promoter region of Acta and acrR was located in 4367-4507 bases and the SD sequence was in 4373-4377 bases.Conclusion:The multiple-antibiotic-resistant active efflux system gene acrAB of Salmonella typhi shows high homology in bases,amino acids and protein structure with that of Escherichia coli and it is the possible reason that Salmonella typhi is resistant to multi-antibiotics without similar chemical structure.更多还原