口腔链球菌密度感应信号系统comE基因及luxS基因的检测分析

Detection and analysis of comE and luxS genes in quorum sensing signal pathway from Streptococcus oralis

目的检测口腔链球菌密度感应系统中的2个重要基因comE以及luxS。方法选取口腔链球菌临床分离株NH521为研究对象,提取基因组DNA,通过聚合酶链式反应进行电泳鉴定和DNA测序,并与GenBank数据库中相关序列进行比较分析。结果电泳鉴定表明口腔链球菌NH521存在comE和LuxS基因。所测序列与GenBank相关序列比较分析表明:luxS、comE基因在口腔链球菌种内不同株系间的DNA序列一致度分别为95.0%和99.6%;对比口腔链球菌与变异链球菌,luxS和comE基因的DNA序列一致度分别为74.1%和12.7%。结论口腔链球菌NH521中存在comE和luxS基因序列,并且luxS基因在种内不同株系间比comE基因积累了更多变异,而comE基因在不同链球菌物种间却更加分化。

Objective To detect and analyze two important genes,comE and luxS,in quorum sensing signal pathway from Streptococcus oralis（S.oralis）.Methods The total genomic DNA of S.oralis NH521（a clinically isolated strain） was firstly extracted.The comE and luxS genes were then amplified by polymerase chain reaction（PCR） and further sequenced.The obtained sequences were compared with related sequences in GenBank.Results Target bands of both comE and luxS genes were detected by electrophoresis.The obtained gene sequences were similar to the corresponding sequences from another S.oralis strain（luxS,95.0%;comE,99.6%）;however,comparing to gene sequences of another species Streptococcus mutans,comE was more divergent（12.7%） than luxS gene（74.1%）.Conclusion This study success-fully amplified and sequenced comE and luxS genes from S.oralis NH521 strain.The luxS gene accumulated more muta-tions than comE gene did between two S.oralis strains,but comE gene is more divergent than luxS gene between two Streptococcus species.