Neural Engineering Center, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Avenue, Shenzhen University Town, Nanshan District, Shenzhen 518055, China.
J Theor Biol. 2011 Sep 21;285(1):77-83. doi: 10.1016/j.jtbi.2011.06.011. Epub 2011 Jun 22.
The left-handed beta-helix (LβH) has received interest recently as it folds as a possible solution for the structure of misfolded proteins associated with prion and Huntington's diseases. Through a combination of sequence and structure analysis, we uncover a novel feature that is common to this unique fold: a two-fold symmetry in both sequence and structure, and this feature always coupled with extended loops in the middle of the helix. Since the results reveal a two-fold symmetric pattern both in the sequence and structure, it may indicate that the symmetry in tertiary structure is coded by the symmetry in primary sequence, which agrees with Anfisen's proposal that a protein's amino-acid sequence specify its three-dimensional structure. It may also indicate that LβH adopts a two-fold repeat pattern during the evolution process and symmetry helps maintaining the stability of the helix structure. The two-fold symmetric pattern and extended loops might be important in maintaining stability of helix proteins. This discovery can be useful in understanding the folding mechanisms of this protein fold and provide insights in the relation between sequences and structures.
左手β-螺旋（LβH）最近受到关注，因为它可能是与朊病毒和亨廷顿病相关的错误折叠蛋白结构的解决方案。通过序列和结构分析的结合，我们发现了一个普遍存在于这种独特折叠中的新特征：序列和结构中的两重对称，并且该特征总是与螺旋中间的扩展环相关联。由于结果揭示了序列和结构中的双重对称模式，这可能表明三级结构中的对称性是由一级序列中的对称性编码的，这与 Anfisen 的提议一致，即蛋白质的氨基酸序列指定其三维结构。它也可能表明 LβH 在进化过程中采用了双重重复模式，对称性有助于保持螺旋结构的稳定性。两重对称模式和扩展环可能在维持螺旋蛋白的稳定性方面起着重要作用。这一发现有助于理解这种蛋白质折叠的折叠机制，并为序列和结构之间的关系提供深入的见解。
