Dawe R Kelly, Henikoff Steven
Department of Plant Biology, University of Georgia, Athens, GA 30602, USA.
Trends Biochem Sci. 2006 Dec;31(12):662-9. doi: 10.1016/j.tibs.2006.10.004. Epub 2006 Oct 30.
A defining feature of chromosomes is the centromere, the site for spindle attachment at mitosis and meiosis. Intriguingly, centromeres of plants and animals are maintained by both sequence-specific and sequence-independent (epigenetic) processes. Epigenetic inheritance might enable kinetochores (the structures that attach centromeres to spindles) to maintain an optimal size. However, centromeres are susceptible to the evolution of "selfish" DNA repeats that bind to kinetochore proteins. We argue that such sequence-specific interactions are evolutionarily unstable because they enable repeat arrays to influence kinetochore size. Changes in kinetochore size could affect the interaction of kinetochores with the spindle and, in principle, skew Mendelian segregation. We propose that key kinetochore proteins have adapted to disrupt such sequence-specific interactions and restore epigenetic inheritance.
染色体的一个决定性特征是着丝粒，它是有丝分裂和减数分裂时纺锤体附着的位点。有趣的是，植物和动物的着丝粒由序列特异性和序列非依赖性（表观遗传）过程共同维持。表观遗传遗传可能使动粒（将着丝粒与纺锤体相连的结构）保持最佳大小。然而，着丝粒容易受到与动粒蛋白结合的“自私”DNA重复序列进化的影响。我们认为，这种序列特异性相互作用在进化上是不稳定的，因为它们使重复序列阵列能够影响动粒大小。动粒大小的变化可能会影响动粒与纺锤体的相互作用，原则上会扭曲孟德尔分离。我们提出，关键的动粒蛋白已经进化以破坏这种序列特异性相互作用并恢复表观遗传遗传。
