Non-linearity of the collagen triple helix in solution and implications for collagen function.
Non-linearity of the collagen triple helix in solution and implications for collagen function.
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DOI：
10.1042/bcj20170217
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发表时间：
2017-06-16
期刊：
影响因子：
--
通讯作者：
Perkins SJ
中科院分区：
文献类型：
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作者：
Walker KT;Nan R;Wright DW;Gor J;Bishop AC;Makhatadze GI;Brodsky B;Perkins SJ
胶原蛋白采用特征性的超螺旋三螺旋构象，其需要重复的（Xaa-Yaa-Gly）n序列。尽管丰富的胶原蛋白，结合实验和原子建模方法迄今尚未量化的灵活性程度实验中看到的胶原蛋白三螺旋的解决方案结构。为了解决这个问题，我们报告了一个实验研究的灵活性不同长度的胶原蛋白三螺旋肽，组成的六，八，十和十二个重复的最稳定的Pro-Hyp-Gly（POG）单位。此外，将一种未封闭的肽（POG）10 unblocked与作为末端效应显著性的对照的封闭的（POG）10进行比较。互补的分析ultracenthegation和同步辐射小角X-射线散射数据表明，较长的三螺旋肽的构象不能很好地解释来自晶体学的线性结构。为了解释这些数据，分子动力学模拟用于为每个螺旋生成50 000个物理上真实的胶原结构。将这些结构与它们各自的散射数据进行拟合，以揭示来自这个可能的螺旋结构的大集合的最佳拟合结构。该曲线拟合证实了这些最佳拟合三螺旋中存在小程度的非线性，弯曲程度近似为线性的4-17°。我们的研究结果为进一步研究具有不同序列和稳定性的其他胶原三螺旋开辟了道路，以阐明分子刚性和柔性在胶原细胞外和免疫功能以及疾病中的作用。
Collagen adopts a characteristic supercoiled triple helical conformation which requires a repeating (Xaa-Yaa-Gly)n sequence. Despite the abundance of collagen, a combined experimental and atomistic modelling approach has not so far quantitated the degree of flexibility seen experimentally in the solution structures of collagen triple helices. To address this question, we report an experimental study on the flexibility of varying lengths of collagen triple helical peptides, composed of six, eight, ten and twelve repeats of the most stable Pro-Hyp-Gly (POG) units. In addition, one unblocked peptide, (POG)10unblocked, was compared with the blocked (POG)10 as a control for the significance of end effects. Complementary analytical ultracentrifugation and synchrotron small angle X-ray scattering data showed that the conformations of the longer triple helical peptides were not well explained by a linear structure derived from crystallography. To interpret these data, molecular dynamics simulations were used to generate 50 000 physically realistic collagen structures for each of the helices. These structures were fitted against their respective scattering data to reveal the best fitting structures from this large ensemble of possible helix structures. This curve fitting confirmed a small degree of non-linearity to exist in these best fit triple helices, with the degree of bending approximated as 4–17° from linearity. Our results open the way for further studies of other collagen triple helices with different sequences and stabilities in order to clarify the role of molecular rigidity and flexibility in collagen extracellular and immune function and disease.