Sequence-specific physical properties of African green monkey alpha-satellite DNA contribute to centromeric heterochromatin formation
Sequence-specific physical properties of African green monkey alpha-satellite DNA contribute to centromeric heterochromatin formation
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DOI：
10.1016/j.jsb.2009.03.010
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发表时间：
2009-07-01
影响因子：
3
通讯作者：
Bennink, Martin L.
中科院分区：
文献类型：
--
作者：
Bussiek, Malte;Hoischen, Christian;Bennink, Martin L.
卫星DNA是真核生物着丝粒异染色质的主要组成部分，可能与确保细胞分裂过程中遗传物质的忠实分离有关。研究了非洲绿色猴（AGM）α-卫星DNA（AS）的结构特征。原子力显微镜成像显示AS片段的端到端距离小于随机序列DNA的持久长度。测定了AS的表观余辉长度为35 nm。凝胶电泳表明，只有一个微弱的贡献的固有曲率的DNA构象，这表明一个额外的贡献的提高弯曲的灵活性减少端到端的距离。接下来，我们利用光镊研究了裸AS和与核小体复合的AS的力延伸行为。裸露的AS显示出降低的过度拉伸过渡力（约为随机DNA测定值的18%）和拉直DNA所需的更高的力。最后，重组AS核小体破坏在显着更高的力量相比，随机DNA核小体，这可能是由于稳定核小体的AS的结构特性。数据支持AS由于特定的结构特性在着丝粒异染色质的形成中起作用，并表明核小体相对较高的机械稳定性在AGM-AS染色质中是重要的。(C)2009爱思唯尔公司All rights reserved.
Satellite DNA, a major component of eukaryotic centromeric heterochromatin, is potentially associated with the processes ensuring the faithful segregation of the genetic material during cell division. Structural properties of alpha-satellite DNA (AS) from African green monkey (AGM) were studied. Atomic force microscopy imaging showed smaller end-to-end distances of AS fragments than would be expected for the persistence length of random sequence DNA. The apparent persistence length of the AS was determined as 35 nm. Gel-electrophoresis indicated only a weak contribution of intrinsic curvature to the DNA conformations suggesting an additional contribution of an elevated bending flexibility to the reduced end-to-end distances. Next, the force-extension behavior of the naked AS and in complex with nucleosomes was studied using optical tweezers. The naked AS showed a reduced overstretching transition force (-18% the value determined for random DNA) and higher forces required to straighten the DNA. Finally, reconstituted AS nucleosomes disrupted at significantly higher forces as compared with random DNA nucleosomes which is probably due to structural properties of the AS which stabilize the nucleosomes. The data support that the AS plays a role in the formation of centromeric heterochromatin due to specific structural properties and suggest that a relatively higher mechanical stability of nucleosomes is important in AGM-AS chromatin. (C) 2009 Elsevier Inc. All rights reserved.