Structural basis for regiospecific midazolam oxidation by human cytochrome P450 3A4
Structural basis for regiospecific midazolam oxidation by human cytochrome P450 3A4
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DOI：
10.1073/pnas.1616198114
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发表时间：
2017-01-17
影响因子：
11.1
通讯作者：
Poulos, Thomas L.
中科院分区：
文献类型：
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作者：
Sevrioukova, Irina F.;Poulos, Thomas L.
人细胞色素 P450 3A4 (CYP3A4) 是一种主要的肝脏和肠道酶，可氧化 60% 以上的给药治疗药物。了解 CYP3A4 如何调整和重塑活性位点以区域选择性氧化化学多样化的化合物对于更好地理解这种重要酶的结构功能关系、改善药物代谢预测的结果以及开发代谢能力下降并导致有害药物相互作用的药物至关重要。然而，迄今为止，有关 CYP3A4-底物相互作用的结构信息非常有限。尽管有各种各样的药物在进行代谢，但只有镇静咪达唑仑 (MDZ) 可以作为体内活性评估的标记底物，因为它优先被 CYP3A4 区域选择性氧化。我们解析了 CYP3A4-MDZ 复合物的 2.7 埃晶体结构，其中药物被明确定义并定向适合 C1 原子（代谢的主要位点）的羟基化。这种结合模式需要与 Ser119 形成氢键，并在 F-G 片段中发生显着的构象转换，从而传递到相邻的 D、E、H 和 I 螺旋，从而导致活性位点空腔崩溃和 MDZ 固定。除了提供关于底物触发的活性位点重塑（诱导拟合）的见解之外，晶体结构还解释了累积的实验结果，识别了可能的效应子结合位点，并表明了为什么 MDZ 主要由 CYP3A 酶亚家族代谢。
Human cytochrome P450 3A4 (CYP3A4) is a major hepatic and intestinal enzyme that oxidizes more than 60% of administered therapeutics. Knowledge of how CYP3A4 adjusts and reshapes the active site to regioselectively oxidize chemically diverse compounds is critical for better understanding structure-function relations in this important enzyme, improving the outcomes for drug metabolism predictions, and developing pharmaceuticals that have a decreased ability to undergo metabolism and cause detrimental drug-drug interactions. However, there is very limited structural information on CYP3A4-substrate interactions available to date. Despite the vast variety of drugs undergoing metabolism, only the sedative midazolam (MDZ) serves as a marker substrate for the in vivo activity assessment because it is preferentially and regioselectively oxidized by CYP3A4. We solved the 2.7 angstrom crystal structure of the CYP3A4-MDZ complex, where the drug is well defined and oriented suitably for hydroxylation of the C1 atom, the major site of metabolism. This binding mode requires H-bonding to Ser119 and a dramatic conformational switch in the F-G fragment, which transmits to the adjacent D, E, H, and I helices, resulting in a collapse of the active site cavity and MDZ immobilization. In addition to providing insights on the substrate-triggered active site reshaping (an induced fit), the crystal structure explains the accumulated experimental results, identifies possible effector binding sites, and suggests why MDZ is predominantly metabolized by the CYP3A enzyme subfamily.