霍乱弧菌山梨醇发酵相关基因序列特征分析

Sequence analysis on sorbitol fermentation related genes in Vibrio cholerae

目的比较霍乱弧菌流行株与非流行株山梨醇发酵相关基因的差异,为采用分子生物学方法快速区分两类菌株提供理论依据。方法采用基因测序的方法,分别对42株霍乱弧菌(O1群埃尔托型33株、O139群9株)流行株和非流行株的糖发酵激活蛋白、外周质麦芽糖结合蛋白、外周质磷酸盐结合蛋白和外周质氨基酸结合蛋白编码基因进行序列比较。结果糖发酵激活蛋白编码基因在霍乱弧菌流行株与非流行株共发现三个位置有单个碱基的差异,即第106、150和378位核苷酸(在流行株分别为A、A和T,而在非流行株分别为G、G和C)。第106位碱基的差异导致了氨基酸的不同(编码蛋白的第36个氨基酸在流行株和非流行株分别为苏氨酸和丙氨酸)。外周质麦芽糖结合蛋白和外周质磷酸盐结合蛋白编码基因各发现两个碱基的规律变化,外周质氨基酸结合蛋白编码基因未发现一致性碱基改变。结论在这些基因中存在着多个单核苷酸多态性,可能会成为快速区分两类菌株的重要依据。糖发酵激活蛋白第36位氨基酸的改变,可能会引起该蛋白活性的改变。

Objective To Investigate the differences of sorbitol fermentation related genes and optimize molecular analysis method for distinguishing an epidemic with nonepidemic strains of Vibrio cholerae. Methods Sequence analysis on four genes of sugar fermentation stimulation protein, periplasmic maltose-binding protein,periplasmic phosphate-binding protein and periplasmic amino acid-binding protein. Results In this study,the following data was noticed: for O1 serogroup El Tor biotype V.cholerae, twenty-four epidemic and eight nonepidemic strains were chosen; For O139 serogroup V.cholerae, five epidemic and four nonepidemic strains were chosen. With those genes of sugar fermentation stimulation protein, there were three point mutations. The 106 th,150 th,378 th oligonucleotide in epidemic strains were A, A and T, comparing to the nonepidemic strains which were G, G and C. When comparing the protein sequences, epidemic strains had a Threonine at 36 th amino acid, whereas nonepidemic strains had an Alanine. The results in O139 serogroup were consistent with those in O1 serogroup El Tor biotype strains. Another two point mutations were found in the genes of periplasmic maltose-binding protein. The 999 th, 1003 th oligonucleotides in epidemic strains were A and C, while in nonepidemic which were G and T. For the gene of periplasmic amino acid-binding protein, two point mutations were noticed. The 504 th and 690 th oligonucleotides in epidemic strains were T and C, but were C and T in nonepidemic. However, no amino acid differences were found in periplasmic maltose-binding protein and periplasmic amino acid-binding protein. For periplasmic amino acid-binding protein gene, there was no difference on oligonucleotide between epidemic and nonepidemic strains. Conclusion Results suggested that SNPs in these genes might serve as a useful tool to distinguish the epidemic strains from nonepidemic strains. The 36 th amino acid mutation of sugar fermentation stimulation protein in epidemic and nonepidemic strains might change the activity of the protein which might be associated with sorbitol fermentation.