GENES INVOLVED IN HAEMOPHILUS-INFLUENZAE TYPE-B CAPSULE EXPRESSION ARE FREQUENTLY AMPLIFIED
GENES INVOLVED IN HAEMOPHILUS-INFLUENZAE TYPE-B CAPSULE EXPRESSION ARE FREQUENTLY AMPLIFIED
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DOI：
10.1093/infdis/167.2.356
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发表时间：
1993-02-01
影响因子：
6.4
通讯作者：
HOISETH, SK
中科院分区：
文献类型：
--
作者：
CORN, PG;ANDERS, J;HOISETH, SK
参与 b 型流感嗜血杆菌荚膜表达的基因以大约 18 kb DNA 片段（Cap b 基因座）的重复形式存在。先前已经表明，重组发生在重复的两个拷贝之间，导致一个拷贝的缺失和胶囊表达的丢失，频率为0.1%-0.5%。本研究测试了这样的假设：重复的排列可以作为进一步扩增荚膜基因序列的模板。对 66 个 B 型入侵分离株的 Southern 杂交分析显示，存在扩增，并且较为常见（23/66 被扩增）。除了 18 kb 重复序列的 3 个拷贝外，在某些菌株中还检测到了 4 个拷贝。 1 个分离株中最多有 5 个拷贝。通过 ELISA，五拷贝菌株产生的荚膜多糖比同基因二拷贝衍生物多约六倍。重复排列的进化意义可能在于它能够在有利于产生更多胶囊的条件下快速扩增。
The genes involved in Haemophilus influenzae type b capsule expression are present as a duplication of an approximately 18-kb DNA segment (the Cap b locus). It has been shown previously that recombination occurs between the two copies of the repeat, resulting in deletion of one copy and loss of capsule expression at frequencies of 0.1%-0.5%. The present study tested the hypothesis that the duplicated arrangement could serve as a template for further amplification of capsule gene sequences. Southern hybridization analysis of 66 type b invasive isolates showed that amplifications exist and are moderately common (23/66 were amplified). In addition to three copies of the 18-kb repeat, four copies were detected in some strains. and up to five copies in 1 isolate. By ELISA, a five-copy strain made about six times more capsular polysaccharide than did an isogenic two-copy derivative. The evolutionary significance of the duplicated arrangement may be its ability to rapidly amplify under conditions where it is advantageous to produce more capsule.