Membrane-Anchored Cytochrome P450 1A2-Cytochrome b5 Complex Features an X-Shaped Contact between Antiparallel Transmembrane Helices
Membrane-Anchored Cytochrome P450 1A2-Cytochrome b5 Complex Features an X-Shaped Contact between Antiparallel Transmembrane Helices
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DOI：
10.1021/acs.chemrestox.5b00349
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发表时间：
2016-04-01
影响因子：
4.1
通讯作者：
Martinek, Vaclav
中科院分区：
文献类型：
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作者：
Jerabek, Petr;Florian, Jan;Martinek, Vaclav
真核细胞色素P450（P450）是一种膜结合酶，可氧化广谱疏水底物，包括外源性物质。蛋白质相互作用在这个过程中起着关键作用。特别是，P450与内质网膜的另一种蛋白质细胞色素B（5）（cyt B（5））形成的瞬时复合物决定了几种P450的催化活性。为了为研究这些效应奠定结构基础，我们构建了一个膜结合全长人P450 1A 2-cyt B（5）复合物的模型。该模型是组装从几个部分使用多尺度建模方法，涵盖了所有的原子和粗粒度的分子动力学（MD）。对于可溶性P450 1A 2-cyt B（5）复合物，这些模拟产生了三种稳定的结合模式（sA（I）、sA（II）和sB）。使用自组装MD用磷脂双层重构跨膜跨膜结构域。预测的全长膜结合复合物（mAI和mB）的特点是自发形成的反平行跨膜结构域之间的X形接触，而mA，模式被发现是不稳定的膜环境。结合模式mA（I）中可溶性结构域的相互位置类似于sA（I）复合物。具有最大的接触面积，最小的结构灵活性，最短的电子转移距离，和最高数量的蛋白质间盐桥，模式mA（I）是催化相关的全长复合物的最佳候选者。
Eukaryotic cytochromes P450 (P450) are membrane-bound enzymes oxidizing a broad spectrum of hydrophobic substrates, including xenobiotics. Protein protein interactions play a critical role in this process. In particular, the formation of transient complexes of P450 with another protein of the endoplasmic reticulum membrane, cytochrome b(5) (cyt b(5)), dictates catalytic activities of several P450s. To lay a structural foundation for the investigation of these effects, we constructed a model of the membrane-bound full-length human P450 1A2-cyt b(5) complex. The model was assembled from several parts using a multiscale modeling approach covering all-atom and coarse grained molecular dynamics (MD). For soluble P450 1A2-cyt b(5) complexes, these simulations yielded three stable binding modes (sA(I), sA(II), and sB). The membrane-spanning transmembrane domains were reconstituted with the phospholipid bilayer using self-assembly MD. The predicted full-length membrane-bound complexes (mAI and mB) featured a spontaneously formed X-shaped contact between antiparallel transmembrane domains, whereas the mA,, mode was found to be unstable in the membrane environment. The mutual position of soluble domains in binding mode mA(I) was analogous to the sA(I) complex. Featuring the largest contact area, the least structural flexibility, the shortest electron transfer distance, and the highest number of interprotein salt bridges, mode mA(I) is the best candidate for the catalytically relevant full-length complex.