Functional dynamics of the folded ankyrin repeats of I kappa B alpha revealed by nuclear magnetic resonance.
Functional dynamics of the folded ankyrin repeats of I kappa B alpha revealed by nuclear magnetic resonance.
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DOI：
10.1021/bi900712r
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发表时间：
2009-08-25
期刊：
影响因子：
2.9
通讯作者：
Komives, Elizabeth A.
中科院分区：
文献类型：
--
作者：
Cervantes, Carla F.;Markwick, Phineus R. L.;Sue, Shih-Che;McCammon, J. Andrew;Dyson, H. Jane;Komives, Elizabeth A.
核因子κB（NF-κB）的抑制主要通过IκBα来实现，I κ B α由N端的信号应答序列、结合NF-κB的六锚蛋白重复结构域（ARD）和C端的PEST序列组成。先前的ARD研究表明，在NF-κB缺失的情况下，第五和第六重复序列仅部分折叠。在这里，我们报告了IκBα截短版本的NMR研究，该版本仅包含前四个锚蛋白重复序列，即IκBα（67−206）。这四个重复段在自由状态下结构良好，使得能够进行充分的共振分配。H-D交换、主链动力学和残余偶极耦合（RDC）实验揭示了灵活性的区域。此外，与微毫秒运动的存在相一致的区域在整个重复结构中周期性地发生。RDCs与晶体结构的比较只得到了中等的协议，但加速分子动力学产生的结构的合奏得到更好的协议与测得的RDCs。显示出柔性的区域对应于那些涉及结合NF-κB后锚蛋白重复序列5和6中柔性损失的熵补偿的区域。游离蛋白中显示微毫秒运动的区域是与复合物中NF-κB直接相互作用的β-发夹的末端。
Inhibition of nuclear factor κB (NF-κB) is mainly accomplished by IκBα, which consists of a signal response sequence at the N-terminus, a six-ankyrin repeat domain (ARD) that binds NF-κB, and a C-terminal PEST sequence. Previous studies with the ARD revealed that the fifth and sixth repeats are only partially folded in the absence of NF-κB. Here we report NMR studies of a truncated version of IκBα, containing only the first four ankyrin repeats, IκBα(67−206). This four-repeat segment is well-structured in the free state, enabling full resonance assignments to be made. H−D exchange, backbone dynamics, and residual dipolar coupling (RDC) experiments reveal regions of flexibility. In addition, regions consistent with the presence of micro- to millisecond motions occur periodically throughout the repeat structure. Comparison of the RDCs with the crystal structure gave only moderate agreement, but an ensemble of structures generated by accelerated molecular dynamics gave much better agreement with the measured RDCs. The regions showing flexibility correspond to those implicated in entropic compensation for the loss of flexibility in ankyrin repeats 5 and 6 upon binding to NF-κB. The regions showing micro- to millisecond motions in the free protein are the ends of the β-hairpins that directly interact with NF-κB in the complex.
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影响因子：
64.5
作者：
Huxford, T;Huang, DB;Ghosh, G
通讯作者：
Ghosh, G
影响因子：
2.7
作者：
DELAGLIO, F;GRZESIEK, S;BAX, A
通讯作者：
BAX, A
影响因子：
64.8
作者：
Chen, FE;Huang, DB;Ghosh, G
通讯作者：
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影响因子：
4.4
作者：
Hamelberg, D;Mongan, J;McCammon, JA
通讯作者：
McCammon, JA
DOI：
10.1002/prot.340170110
发表时间：
1993-09-01
期刊：
PROTEINS-STRUCTURE FUNCTION AND GENETICS
影响因子：
--
作者：
BAI, YW;MILNE, JS;ENGLANDER, SW
通讯作者：
ENGLANDER, SW