Schouls Leo M, Schot Corrie S, Jacobs Jan A
Laboratory for Vaccine-Preventable Diseases, National Institute of Public Health and the Environment, Bilthoven, The Netherlands.
J Bacteriol. 2003 Dec;185(24):7241-6. doi: 10.1128/JB.185.24.7241-7246.2003.
The nature in variation of the 16S rRNA gene of members of the Streptococcus anginosus group was investigated by hybridization and DNA sequencing. A collection of 708 strains was analyzed by reverse line blot hybridization. This revealed the presence of distinct reaction patterns representing 11 different hybridization groups. The 16S rRNA genes of two strains of each hybridization group were sequenced to near-completion, and the sequence data confirmed the reverse line blot hybridization results. Closer inspection of the sequences revealed mosaic-like structures, strongly suggesting horizontal transfer of segments of the 16S rRNA gene between different species belonging to the Streptococcus anginosus group. Southern blot hybridization further showed that within a single strain all copies of the 16S rRNA gene had the same composition, indicating that the apparent mosaic structures were not PCR-induced artifacts. These findings indicate that the highly conserved rRNA genes are also subject to recombination and that these events may be fixed in the population. Such recombination may lead to the construction of incorrect phylogenetic trees based on the 16S rRNA genes.
通过杂交和DNA测序研究了咽峡炎链球菌群成员16S rRNA基因的变异性质。采用反向线印迹杂交分析了708株菌株。结果显示存在代表11个不同杂交组的独特反应模式。对每个杂交组的两株菌株的16S rRNA基因进行了近乎完整的测序，序列数据证实了反向线印迹杂交结果。对序列的进一步检查揭示了镶嵌样结构，强烈提示16S rRNA基因片段在属于咽峡炎链球菌群的不同物种之间发生了水平转移。Southern印迹杂交进一步表明，在单个菌株内，16S rRNA基因的所有拷贝具有相同的组成，表明明显的镶嵌结构不是PCR诱导的假象。这些发现表明，高度保守的rRNA基因也会发生重组，并且这些事件可能在群体中固定下来。这种重组可能导致基于16S rRNA基因构建错误的系统发育树。
