MODIFICATION OF TELOMERIC DNA IN TRYPANOSOMA-BRUCEI - A ROLE IN ANTIGENIC VARIATION
MODIFICATION OF TELOMERIC DNA IN TRYPANOSOMA-BRUCEI - A ROLE IN ANTIGENIC VARIATION
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DOI：
10.1093/nar/12.10.4153
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发表时间：
1984-01-01
影响因子：
14.9
通讯作者：
BORST, P
中科院分区：
文献类型：
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作者：
BERNARDS, A;VANHARTENLOOSBROEK, N;BORST, P
布氏锥虫表面抗原基因的表达发生在端粒附近的表达位点。由于一次仅产生一种抗原，因此必须存在一种机制来防止多个表达位点同时活动。在这里，我们报告沉默端粒抗原基因中的 PstI 和 PvuII 限制性位点部分不可切割，大概是 DNA 修饰的结果。这种修饰在转录基因中不存在，但在基因失活后又恢复，可能是端粒 DNA 所特有的，因为 (1) 在非端粒基因中未检测到这种修饰； (2)靠近端粒修饰最高； (3)端粒基因的修饰水平受下游端粒DNA片段大小的影响。端粒修饰是抗原基因关闭的原因还是结果仍有待确定。
Expression of surface antigen genes inTrypanosoma bruceioccurs at expression sites located near telomeres. Since only one antigen is produced at a time, a mechanism must exist to prevent the simultaneous activity of multiple expression sites. Here we report that PstI and PvuII restriction sites in silent telomeric antigen genes are partially uncleavable, presumably as a consequence of DNA modification. The modification, which is absent in transcribed genes but returns after gene inactivation, may be specific for telomeric DNA because (1) it is not detected in non-telomeric genes; (2) modification is highest close to the telomere; (3) the level of modification in a telomeric gene is influenced by the size of the telomeric DNA segment downstream. Whether telomere modification is cause or consequence of antigen gene switch-off remains to be determined.