Evolutionary genetics of the capsular locus of serogroup 6 pneumococci
Evolutionary genetics of the capsular locus of serogroup 6 pneumococci
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DOI：
10.1128/jb.186.24.8181-8192.2004
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发表时间：
2004-12-01
影响因子：
3.2
通讯作者：
Spratt, BG
中科院分区：
文献类型：
--
作者：
Mavroidi, A;Godoy, D;Spratt, BG
通过分析102株6A型和613株6A型肺炎链球菌的3个血清型特异性cps基因的序列变异，研究了6A型肺炎链球菌cps基因座的进化。这些CPS基因内的序列变异与菌株的遗传相关性有关，由多位点序列分型确定，并与最近进化的推断模式有关，使用eBURST算法探索。血清型6A和613分离株的cps基因G + C百分比较低，该区域的序列多样性水平较低。在这些血清型之间也存在很少的序列差异，表明单一引入祖先cps序列，随后轻微差异产生血清型6A和6B。少数血清型613分离株的cps序列（2类序列）与其他血清型613分离株的cps序列（1类序列）相似，差异为5%，可能是最近从相关但不同的来源第二次引入的。血清型6A或6B荚膜的表达与wciP（鼠李糖转移酶基因）内的单一非同义多态性完全相关。除了血清型6A和6B cps基因座水平转移到不相关谱系的充分证据外，在非常密切相关的分离株和最近1类和2类cps血清组6序列之间重组事件的实例中，有证据表明血清型6A到613的变化相对频繁，反之亦然。
The evolution of the capsular biosynthetic (cps) locus of serogroup 6 Streptococcus pneumoniae was investigated by analyzing sequence variation within three serotype- specific cps genes from 102 serotype 6A and 613 isolates. Sequence variation within these cps genes was related to the genetic relatedness of the isolates, determined by multilocus sequence typing, and to the inferred patterns of recent evolutionary descent, explored using the eBURST algorithm. The serotype-specific cps genes had a low percent G + C, and there was a low level of sequence diversity in this region among serotype 6A and 613 isolates. There was also little sequence divergence between these serotypes, suggesting a single introduction of an ancestral cps sequence, followed by slight divergence to create serotypes 6A and 6B. A minority of serotype 613 isolates had cps sequences (class 2 sequences) that were similar to5% divergent from those of other serotype 613 isolates (class 1 sequences) and which may have arisen by a second, more recent introduction from a related but distinct source. Expression of a serotype 6A or 6B capsule correlated perfectly with a single nonsynonymous polymorphism within wciP, the rhamnosyl transferase gene. In addition to ample evidence of the horizontal transfer of the serotype 6A and 6B cps locus into unrelated lineages, there was evidence for relatively frequent changes from serotype 6A to 613, and vice versa, among very closely related isolates and examples of recent recombinational events between class 1 and 2 cps serogroup 6 sequences.