Mapping the Effect of Gly Mutations in Collagen on α2β1 Integrin Binding.
Mapping the Effect of Gly Mutations in Collagen on α2β1 Integrin Binding.
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DOI：
10.1074/jbc.m116.726182
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发表时间：
2016-09-02
期刊：
影响因子：
--
通讯作者：
Brodsky B
中科院分区：
文献类型：
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作者：
Yigit S;Yu H;An B;Hamaia S;Farndale RW;Kaplan DL;Lin YS;Brodsky B
I型胶原三螺旋的基本重复三肽序列中的一个Gly的替换导致显性遗传性骨疾病成骨不全。导致病理学的机制可能涉及错误折叠和自噬，尽管已经假设一些突变干扰已知的胶原相互作用。在此，使用重组细菌胶原系统研究了整合素结合GFPGER序列内和附近的Gly置换的影响。当将含有GFPGER的六联体人I型胶原序列引入细菌胶原样蛋白时，这种嵌合蛋白与整联蛋白结合。在插入的人序列内和附近具有Gly至Ser取代的构建体仍然形成胰蛋白酶抗性三螺旋，这表明小的局部构象扰动。Gly到Ser的突变内的两个Gly残基在必需的GFPGER序列防止整合素结合和细胞附着的复杂的分子动力学研究预测。Gly残基C-末端替换为GFPGER不影响整合素结合。相比之下，Gly替换GFPGER序列的N-末端，最多四个三联体，降低了整合素结合和细胞粘附。这种模式表明，在初始结合中涉及GFPGER的N-末端三联体或三螺旋C-末端的扰动传播到突变位点。相对于突变位点的生物学后果的不对称性可能与观察到的整联蛋白结合位点附近的成骨细胞突变模式有关。
The replacement of one Gly in the essential repeating tripeptide sequence of the type I collagen triple helix results in the dominant hereditary bone disorder osteogenesis imperfecta. The mechanism leading to pathology likely involves misfolding and autophagy, although it has been hypothesized that some mutations interfere with known collagen interactions. Here, the effect of Gly replacements within and nearby the integrin binding GFPGER sequence was investigated using a recombinant bacterial collagen system. When a six-triplet human type I collagen sequence containing GFPGER was introduced into a bacterial collagen-like protein, this chimeric protein bound to integrin. Constructs with Gly to Ser substitutions within and nearby the inserted human sequence still formed a trypsin-resistant triple helix, suggesting a small local conformational perturbation. Gly to Ser mutations within the two Gly residues in the essential GFPGER sequence prevented integrin binding and cell attachment as predicted from molecular dynamics studies of the complex. Replacement of Gly residues C-terminal to GFPGER did not affect integrin binding. In contrast, Gly replacements N-terminal to the GFPGER sequence, up to four triplets away, decreased integrin binding and cell adhesion. This pattern suggests either an involvement of the triplets N-terminal to GFPGER in initial binding or a propagation of the perturbation of the triple helix C-terminal to a mutation site. The asymmetry in biological consequences relative to the mutation site may relate to the observed pattern of osteogenesis imperfecta mutations near the integrin binding site.