Crystal Structure of Cindoxin, the P450cin Redox Partner
Crystal Structure of Cindoxin, the P450cin Redox Partner
复制标题
DOI：
10.1021/bi500010m
复制
发表时间：
2014-03-11
期刊：
影响因子：
2.9
通讯作者：
Poulos, Thomas L.
中科院分区：
文献类型：
--
作者：
Madrona, Yarrow;Hollingsworth, Scott A.;Poulos, Thomas L.
含黄素单核苷酸 (FMN) 的 P450cin 氧化还原伴侣辛多辛 (Cdx) 的晶体结构已确定为 1.3 埃分辨率。整体结构与人细胞色素P450还原酶的FMN结构域相似。使用布朗动力学-分子动力学对接方法生成 Cdx 及其氧化还原伙伴 P450cin 的模型。该 Cdx-P450cin 模型强调了 Cdx Tyr96 在桥接 FMN 和血红素辅因子以及 P450cin Arg102 和 Arg346 方面的潜在重要性。每个单位点 Ala 突变体都表现出与野生型活性相似的 10%，从而证明了这些残基对于结合和/或电子转移的重要性。在经过充分研究的 P450cam 系统中，氧化还原伴侣结合稳定了 P450cam 的开放低自旋构象，并大大降低了氧复合物的稳定性。与此形成鲜明对比的是，Cdx 不会将 P450cin 转变为低自旋状态，尽管 oxy-P450cin 的稳定性在 Cdx 存在下降低了 10 倍。这表明与 P450cam 相比，Cdx 对 P450cin 中的开闭平衡的影响可能较小。据推测，Pdx 在 P450cam 上的部分效应子作用是促进显着的结构变化，从而提供涉及 O-2 激活所需的 Asp251 的质子中继网络。 P450cin 中相应的天冬氨酸 (Asp241) 周围的结构为 P450cin 不太依赖其氧化还原伙伴来实现功能上重要的结构变化提供了可能的结构原因。
The crystal structure of the flavin mononucleotide (FMN)-containing redox partner to P450cin, cindoxin (Cdx), has been determined to 1.3 angstrom resolution. The overall structure is similar to that of the FMN domain of human cytochrome P450 reductase. A Brownian dynamics-molecular dynamics docking method was used to produce a model of Cdx with its redox partner, P450cin. This Cdx-P450cin model highlights the potential importance of Cdx Tyr96 in bridging the FMN and heme cofactors as well P450cin Arg102 and Arg346. Each of the single-site Ala mutants exhibits similar to 10% of the wild-type activity, thus demonstrating the importance of these residues for binding and/or electron transfer. In the well-studied P450cam system, redox partner binding stabilizes the open low-spin conformation of P450cam and greatly decreases the stability of the oxy complex. In sharp contrast, Cdx does not shift P450cin to a low-spin state, although the stability of oxy-P450cin is decreased 10-fold in the presence of Cdx. This indicates that Cdx may have a modest effect on the open-closed equilibrium in P450cin compared to that in P450cam. It has been postulated that part of the effector role of Pdx on P450cam is to promote a significant structural change that makes available a proton relay network involving Asp251 required for O-2 activation. The structure around the corresponding Asp in P450cin, Asp241, provides a possible structural reason for why P450cin is less dependent on its redox partner for functionally important structural changes.