Structure and assembly of the heterotrimeric and homotrimeric C-propeptides of type I collagen: significance of the alpha2(I) chain.
Structure and assembly of the heterotrimeric and homotrimeric C-propeptides of type I collagen: significance of the alpha2(I) chain.
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I 型胶原异源三聚体和同源三聚体 C 前肽的结构和组装：α2(I) 链的重要性。
DOI：
10.1021/bi0508338
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Veis,Arthur
中科院分区：
文献类型：
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作者：
Malone,JamesP;Alvares,Keith;Veis,Arthur
I 型原胶原分子的组装始于 C-pro α1(I) 和 C-pro α2(I) 结构域之间的相互作用。 C-前肽结构域本身具有不同结构的子结构域。重要的问题是链缔合从哪里开始以及导致优先形成[C-pro α1(I)]2[C-pro α2(I)]异三聚体的链选择性的基础。这些问题可以通过单个 C-前肽结构的能量最小化建模、对其对接相互作用的研究以及异源三聚体和同源三聚体 C-pro 结构和稳定性的比较来解决。比较显示 C-pro α2 链对组装的三聚体 C-前肽的结构具有显着影响。在建模中，这三个链通过短的 C 末端胶原三螺旋片段锚定并记录，随后是处于对接构象的 C 端肽，然后允许剩余的 C 前肽链相互作用和对接。令人惊讶的是，前肽三聚化并没有通过先前提出的 C 前肽的 N 端“寡聚化结构域”进行 [McAlinden 等人，2017]。 (2003)J。生物。化学。 278, 42200] 而是在 I 型原胶原链的大多数 C 末端结构域中。分子动力学显示异源三聚体组装以球状 G2α2 和 G2α12 结构域之间的二聚体形成开始，随后在 G1 结构域处三聚化。由于 α2 C 前肽链 N 末端的位置 3、7 和 11 上存在 Pro 残基，因此不可能在推定的寡聚卷曲螺旋结构域中启动组装。为了确认计算结果和提出的组装途径，将 G2α1 和 G2α2 结构域重组制备为麦芽糖结合蛋白构建体，并通过动态光散射和凝胶过滤色谱研究了它们的相互作用。在所检测的MBP仍为单体的条件下，MBP-G2α1和MBP-G2α2单独形成二聚体，但MBP-G2α1和MBP-G2α2的2:1混合物有利于三聚体形成。因此，I 型胶原 C 前肽的 C 端球状结构域 (G2) 在分子间组装和异源三聚体选择性的启动中发挥着至关重要的作用。
Assembly of the type I procollagen molecule begins with interactions among the C-pro α1(I) and C-pro α2(I) domains. The C-propeptide domains themselves have subdomains of distinct structures. The important questions are where chain association begins and the basis of the chain selectivity which leads to the preferential formation of the [C-pro α1(I)]2[C-pro α2(I)] heterotrimer. These questions are addressed by energy minimization modeling of the individual C-propeptide structures, study of their docking interactions, and comparison of the heterotrimeric and homotrimeric C-pro structures and stability. The comparisons show the remarkable impact of the C-pro α2 chain on the structure of the assembled trimeric C-propeptide. In the modeling, the three chains were anchored and registered by a short C-terminal collagen triple-helical segment followed by the C-telopeptides in their docked conformation, and then the remaining C-propeptide chains were allowed to interact and dock. Surprisingly, propeptide trimerization did not proceed through the previously proposed N-terminal “oligomerization domain” of the C-propeptide [McAlinden et al. (2003)J. Biol. Chem. 278, 42200] but rather in the most C-terminal domains of type I procollagen chains. Molecular dynamics showed heterotrimer assembly to begin with dimer formation between globular G2α2 and the G2α12domains followed by trimerization at the G1 domains. Assembly initiation in the putative oligomerization coiled-coil domain is not possible because of the Pro residues at positions 3, 7, and 11 at the N-terminus of the α2 C-propeptide chain. To confirm the computations and proposed assembly pathway, the G2α1 and G2α2 domains were prepared recombinantly as the maltose binding protein constructs, and their interactions were studied by dynamic light scattering and gel filtration chromatography. Under the conditions examined MBP remained as monomer, MBP-G2α1 and MBP-G2α2 alone formed dimers, but a 2:1 mixture of MBP-G2α1 and MBP-G2α2 favored trimer formation. Thus, the C-terminal globular domains (G2) of the type I collagen C-propeptides play a crucial role in the initiation of intermolecular assembly and heterotrimer selectivity.