Structure-Function Analysis of Porcine Cytochrome P450 3A29 in the Hydroxylation of T-2 Toxin as Revealed by Docking and Mutagenesis Studies
作者:Guyue Cheng、Changcun Liu、Xu Wang、Hongmin Ma、Yuanhu Pan、Lingli Huang、Haihong Hao、Menghong Dai、Zonghui Yuan
DOI:10.1371/journal.pone.0106769
日期:——
T-2 toxin, one of the type A trichothecenes, presents a potential hazard to human and animal health. Our previous work demonstrated that porcine cytochrome P450 3A29 (CYP3A29) played an important role in the hydroxylation of T-2 toxin. To identify amino acids involved in this metabolic process, T-2 toxin was docked into a homology model of CYP3A29 based on a crystal structure of CYP3A4 using AutoDock 4.0. Nine residues of CYP3A29, Arg105, Arg106, Phe108, Ser119, Lys212, Phe213, Phe215, Arg372 and Glu374, which were found within 5 Å around T-2 toxin were subjected to site-directed mutagenesis. In the oxidation of nifedipine, the CLint value of R106A was increased by nearly two-folds compared with the wild-type CYP3A29, while the substrate affinities and CLint values of S119A and K212A were significantly reduced. In the hydroxylation of T-2 toxin, the generation of 3′-OH-T-2 by R105A, S119A and K212A was significantly less than that by the wild-type, whereas R106A slightly increased the generation of 3′-OH-T-2. These results were further confirmed by isothermal titration calorimetry analysis, suggesting that these four residues are important in the hydroxylation of T-2 toxin and Arg105 may be a specific recognition site for the toxin. Our study suggests a possible structure-function relationship of CYP3A29 in the hydroxylation of T-2 toxin, providing with new insights into the mechanism of CYP3A enzymes in the biotransformation of T-2 toxin.
T-2 毒素是 A 型单端孢霉烯的一种,对人类和动物健康具有潜在危害。我们之前的研究表明,猪细胞色素 P450 3A29 (CYP3A29) 在 T-2 毒素的羟化过程中发挥了重要作用。为了确定参与这一代谢过程的氨基酸,我们使用 AutoDock 4.0 根据 CYP3A4 的晶体结构将 T-2 毒素与 CYP3A29 的同源模型对接。对 T-2 毒素周围 5 Å 范围内的 CYP3A29 的 9 个残基 Arg105、Arg106、Phe108、Ser119、Lys212、Phe213、Phe215、Arg372 和 Glu374 进行了定点突变。在硝苯地平的氧化过程中,与野生型 CYP3A29 相比,R106A 的 CLint 值增加了近两倍,而 S119A 和 K212A 的底物亲和力和 CLint 值则显著降低。在 T-2 毒素的羟化过程中,R105A、S119A 和 K212A 产生的 3′-OH-T-2 明显少于野生型,而 R106A 则略微增加了 3′-OH-T-2 的产生。等温滴定量热分析进一步证实了这些结果,表明这四个残基在 T-2 毒素的羟基化过程中非常重要,Arg105 可能是毒素的特异性识别位点。我们的研究提示了 CYP3A29 在 T-2 毒素羟化过程中可能存在的结构-功能关系,为了解 CYP3A 酶在 T-2 毒素生物转化过程中的作用机制提供了新的视角。