Ducassou Lionel, Dhers Laura, Jonasson Gabriella, Pietrancosta Nicolas, Boucher Jean-Luc, Mansuy Daniel, André François
UMR 8601 CNRS, University Paris Descartes, Paris Sorbonne Cité, 75270, Paris, France.
University Paris Saclay, I2BC/CNRS UMR 9198, CEA Saclay, 91191, Gif sur Yvette, France.
Biochimie. 2017 Sep;140:166-175. doi: 10.1016/j.biochi.2017.07.007. Epub 2017 Jul 23.
Human cytochrome P450 2U1 (CYP2U1) is an orphan CYP that exhibits several distinctive characteristics among the 57 human CYPs with a highly conserved sequence in almost all living organisms.
We compared its protein sequence with those of the 57 human CYPs and constructed a 3D structure of a full-length CYP2U1 model bound to a POPC membrane. We also performed docking experiments of arachidonic acid (AA) and N-arachidonoylserotonin (AS) in this model.
The protein sequence of CYP2U1 displayed two unique characteristics when compared to those of the human CYPs, the presence of a longer N-terminal region upstream of the putative trans-membrane helix (TMH) containing 8 proline residues, and of an insert of about 20 amino acids containing 5 arginine residues between helices A' and A. Its N-terminal part upstream of TMH involved an additional short terminal helix, in a manner similar to what was reported in the crystal structure of Saccharomyces cerevisiae CYP51. Our model also showed a specific interaction between the charged residues of insert AA' and phosphate groups of lipid polar heads, suggesting a possible role of this insert in substrate recruitment. Docking of AA and AS in this model showed these substrates in channel 2ac, with the terminal alkyl chain of AA or the indole ring of AS close to the heme, in agreement with the reported CYP2U1-catalyzed AA and AS hydroxylation regioselectivities.
This model should be useful to find new endogenous or exogenous CYP2U1 substrates and to interpret the regioselectivity of their hydroxylation.
人类细胞色素P450 2U1（CYP2U1）是一种孤儿细胞色素P450，在57种人类细胞色素P450中具有几个独特特征，其序列在几乎所有生物体中高度保守。
我们将其蛋白质序列与57种人类细胞色素P450的序列进行比较，并构建了与POPC膜结合的全长CYP2U1模型的三维结构。我们还在此模型中进行了花生四烯酸（AA）和N-花生四烯酰基血清素（AS）的对接实验。
与人类细胞色素P450的序列相比，CYP2U1的蛋白质序列显示出两个独特特征，即在假定的跨膜螺旋（TMH）上游存在更长的N端区域，该区域含有8个脯氨酸残基，以及在螺旋A'和A之间存在一个约20个氨基酸的插入片段，其中含有5个精氨酸残基。其TMH上游的N端部分涉及一个额外的短末端螺旋，其方式类似于酿酒酵母CYP51晶体结构中所报道的。我们的模型还显示插入片段AA'的带电残基与脂质极性头部的磷酸基团之间存在特异性相互作用，表明该插入片段在底物募集方面可能发挥作用。在此模型中对AA和AS进行对接显示这些底物位于通道2ac中，AA的末端烷基链或AS的吲哚环靠近血红素，这与报道的CYP2U1催化的AA和AS羟基化区域选择性一致。
该模型应有助于发现新的内源性或外源性CYP2U1底物，并解释其羟基化的区域选择性。
