Different foreign genes incidentally integrated into the same locus of the Streptococcus suis genome
Different foreign genes incidentally integrated into the same locus of the Streptococcus suis genome
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DOI：
10.1128/jb.187.3.872-883.2005
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发表时间：
2005-02-01
影响因子：
3.2
通讯作者：
Shimoji, Y
中科院分区：
文献类型：
--
作者：
Sekizaki, T;Takamatsu, D;Shimoji, Y
一些猪链球菌菌株具有II型限制修饰（RM）系统，其基因被认为是通过非法重组从外源插入到基因组purH和purD之间。在这项研究中，我们的特点是purHD基因座的S。对28株血清型参考菌株的基因组进行了序列测定。如前所述，4个菌株在该基因座中含有RM基因，而11个菌株具有7个类别的其他遗传区域。基因区域包含一个或多个基因，这些基因要么是未知的，要么与其他细菌的假设基因相似。具有非典型G+C含量的遗传区域的互斥定位表明这些区域也是从国外来源获得的。在邻近区域未发现转座因子或长重复序列。包括RM基因区域在内的核苷酸序列的比对表明，外源区域通过短片段核苷酸同一性的非法重组整合。利用温敏性自杀质粒，将RM基因导入S.在该基因座中不含任何外源基因猪菌株。将质粒整合到S.猪的基因组不存在于purHD位点，而是存在于染色体的多个位点，其中染色体与质粒之间存在2 - 10 bp的核苷酸同一性。这些结果表明，这里描述的各种外源基因偶然整合到S.猪的基因组。
Some strains of Streptococcus suis possess a type II restriction-modification (RM) system, whose genes are thought to be inserted into the genome between purH and purD from a foreign source by illegitimate recombination. In this study, we characterized the purHD locus of the S. suis genomes of 28 serotype reference strains by DNA sequencing. Four strains contained the RM genes in the locus, as described before, whereas 11 strains possessed other genetic regions of seven classes. The genetic regions contained a single gene or multiple genes that were either unknown or similar to hypothetical genes of other bacteria. The mutually exclusive localization of the genetic regions with the atypical G+C contents indicated that these regions were also acquired from foreign sources. No transposable element or long-repeat sequence was found in the neighboring regions. An alignment of the nucleotide sequences, including the RM gene regions, suggested that the foreign regions were integrated by illegitimate recombination via short stretches of nucleotide identity. By using a thermosensitive suicide plasmid, the RM genes were experimentally introduced into an S. suis strain that did not contain any foreign genes in that locus. Integration of the plasmid into the S. suis genome did not occur in the purHD locus but occurred at various chromosomal loci, where there were 2 to 10 bp of nucleotide identity between the chromosome and the plasmid. These results suggest that various foreign genes described here were incidentally integrated into the same locus of the S. suis genome.