Recognition between disordered polypeptide chains from cleavage of an alpha/beta domain: self-versus non-self-association.
Recognition between disordered polypeptide chains from cleavage of an alpha/beta domain: self-versus non-self-association.
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识别α/β结构域裂解产生的无序多肽链：自缔合与非自缔合。
DOI：
10.1142/9789814447300_0058
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发表时间：
1999
影响因子：
--
通讯作者：
Tasayco,ML
中科院分区：
文献类型：
--
作者：
Yang,XM;Georgescu,RE;Li,JH;Yu,WF;Haierhan;Tasayco,ML
结构生物学的进展引起了对蛋白质无序状态的生物学意义的重新评估。我们相信，规则，管理无序的多肽链之间的分子识别的结构，稳定性和动力学可以阐明通过研究过程，耦合协会折叠。单结构域蛋白的片段互补重组提供了一个很好的机会来研究它们。由于几乎完整的序列是可用的，虽然不是在单链上，但大多数互补片段预计会重新组装。然而，事实并非如此。我们选择了。大肠杆菌硫氧还蛋白（Trx）是一种小的、单α/β结构域蛋白，作为研究切割位点和数目对互补片段重组的影响的模型系统。我们已经详细地展示了环分裂后的重组（1-73，74-108）1和α-螺旋裂解后（1-37，38- 108）.2尽管两组片段都产生天然样复合物，但在界面几何形状、折叠状态的表观稳定性和缔合/折叠机制方面存在明显差异：（i）1-37/38-108复合物（4 μM）的表观平衡解离常数高于1-73/74-108复合物（49 nM），（ii）非自缔合的表观速率常数相似（约103 M − 1 s −1），以及（iii）在这些实验条件下只有1-37片段自缔合。在这里，自缔合和非自缔合之间的竞争导致明显不稳定的1-37/38-108复合物。
Advances in structural biology have provoked a re-evaluation of the biological significance of the disordered state of proteins. We believe that the rules that govern structure, stability and kinetics in the molecular recognition between disordered polypeptide chains can be elucidated by studying processes that couple association with folding. The reassembly of single domain proteins by fragment complementation provides an excellent opportunity to study them. Since almost the complete sequence is available, although not on a single chain, most of the complementary fragments are expected to reassemble. However, that happens not to be the case. We have chosenE. colithioredoxin (Trx), a small, single α/β-domain protein, as a model system to study the effect of the site and number of cleavages on the reassembly of complementary fragments. We have shown at atomic detail the reassembly after cleavage of a loop (1-73, 74-108)1and after cleavage of an α-helix (1-37, 38- 108).2 Although both sets of fragments produce native-like complexes, there are clear differences in the interface geometry, apparent stability of the folded state and mechanism of association/folding: (i) the apparent equilibrium dissociation constant for 1-37/38-108 complex (4 μM) is higher than the one for 1-73/74-108 complex (49 nM), (ii) the apparent rate constants of non-self-association are similar (about 103M−1s−1), and (iii) only the 1-37 fragment self-associates under these experimental conditions. Here the competition between self- and non-self-association leads to an apparently less stable 1-37/38-108 complex.