Both DNA and histone fold sequences contribute to archaeal nucleosome stability
Both DNA and histone fold sequences contribute to archaeal nucleosome stability
复制标题
DOI：
10.1074/jbc.m110029200
复制
发表时间：
2002-03-15
影响因子：
4.8
通讯作者：
Reeve, JN
中科院分区：
文献类型：
--
作者：
Bailey, KA;Marc, F;Reeve, JN
DNA 序列和古细菌组蛋白折叠结构在确定古细菌核小体稳定性和定位中的作用和相互依赖性已被确定和定量。 pLITMUS28 多接头区域中 TTTAAAGCCG 的四个串联拷贝的存在导致 DNA 分子相对于多接头序列对古菌组蛋白 HAM 具有增加的亲和力（DeltaDeltaG 类似于 700 cal mol(-1)），并且已经确定二核苷酸 TA 的螺旋重复对这种增加的亲和力的主要定量贡献。组装在 (TTTAAAGCCG)4 序列和通过 HMfB 选择性掺入古菌核小体的 DNA 分子上的古菌核小体的旋转和平移定位已经确定。交替富含 A/T 和 G/C 的区域分别位于小沟和大沟处，依次面向古菌核小体核心，并且使用 HMfA（也来自产热甲烷菌）密切相关的古菌组蛋白获得了相同的定位结果。然而，HMfA 对 HMfB 选择的 DNA 分子没有类似的高亲和力，结构域交换实验表明，这种亲和力差异是由组蛋白折叠的 a 螺旋 3 的 C 末端区域的残基差异决定的，该区域预计不会直接与 DNA 相互作用。相反，该区域被认为参与形成古细菌核小体组蛋白四聚体核心中心的组蛋白二聚体：二聚体界面。如果该界面的差异确实导致古细菌组蛋白核心具有不同的序列偏好，那么替代古细菌核小体四聚体核心的组装可以提供一种意想不到的新颖的结构机制来调节基因表达。
The roles and interdependence of DNA sequence and archaeal histone fold structure in determining archaeal nucleosome stability and positioning have been determined and quantitated. The presence of four tandem copies of TTTAAAGCCG in the polylinker region of pLITMUS28 resulted in a DNA molecule with increased affinity (DeltaDeltaG of similar to700 cal mol(-1)) for the archaeal histone HAM relative to the polylinker sequence, and the dominant, quantitative contribution of the helical repeats of the dinucleotide TA to this increased affinity has been established. The rotational and translational positioning of archaeal nucleosomes assembled on the (TTTAAAGCCG)4 sequence and on DNA molecules selectively incorporated into archaeal nucleosomes by HMfB have been determined. Alternating A/T- and G/C-rich regions were located where the minor and major grooves, respectively, sequentially faced the archaeal nucleosome core, and identical positioning results were obtained using HMfA a closely related archaeal histone also from Methanothermus fervidus. However, HMfA did not have similarly high affinities for the HMfB-selected DNA molecules, and domain-swap experiments have shown that this difference in affinity is determined by residue differences in the C-terminal region of a-helix 3 of the histone fold, a region that is not expected to directly interact with DNA. Rather this region is thought to participate in forming the histone dimer:dimer interface at the center of an archaeal nucleosome histone tetramer core. If differences in this interface do result in archaeal histone cores with different sequence preferences, then the assembly of alternative archaeal nucleosome tetramer cores could provide an unanticipated and novel structural mechanism to regulate gene expression.