超变性热点使得Dictyostelium中自我/非自我识别基因的快速演变成为可能
Mische Holland1, Mayar Ahmed1, Janet M Young2
1Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260.
概括
阿米巴Dictyostelium discoideum通过基因重复和重组,快速演变多态TgrB1和TgrC1蛋白质. 这种遗传多样性对于细胞的识别和功能至关重要,类似于哺乳动物的免疫基因.
科学领域:
- 进化生物学是进化的生物学.
- 基因组学就是基因组学.
- 细胞和分子生物学是细胞和分子生物学.
背景情况:
- 细胞中精确的自我/非自我识别依赖于高度多态的受体.
- 在Dictyostelium discoideum中,多态TgrB1和TgrC1蛋白质介导着姐妹细胞的结合和骗子排除.
- 这些基因中产生极端遗传多样性的机制在很大程度上是未知的.
研究的目的:
- 研究Dictyostelium discoideum中大型tgr基因家族的进化动态.
- 了解tgrB1和tgrC1基因的极端遗传多样性是如何产生的.
- 为阿米巴比较基因组学提供全面的基因组资源.
主要方法:
- 从10个D. discoideum分离物和姐妹物种中生成染色体长度,全基因组序列.
- 包括克拉米迪亚类内共生生物的完整基因组.
- 分析了基因家族进化,重点关注tgr locus内的结构动力学和重组.
主要成果:
- tgrB1和tgrC1基因位于一个超突变热点中,其重组,重复,转位和反转率很高.
- 这些结构动态导致相邻基因的频繁增加和丧失,并迅速生成独特的tgrBC谱.
- 更广泛的tgr基因家族表现出可变的进化,其中一些基因 (tgrN) 被保存,而另一些基因 (tgrA) 迅速复制.
结论:
- 在tgrBC位置内的强烈多样化解释了这些基因在D. discoideum的极端多态性.
- 进化机制与哺乳动物的MHC免疫基因和其他allorecognition系统并行.
- 生成的基因组集合可以作为未来Amoebozoa研究的宝贵资源.
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