Crystal Structures of the CERT START Domain with Inhibitors Provide Insights into the Mechanism of Ceramide Transfer
Crystal Structures of the CERT START Domain with Inhibitors Provide Insights into the Mechanism of Ceramide Transfer
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DOI：
10.1016/j.jmb.2009.12.029
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发表时间：
2010-02-19
影响因子：
5.6
通讯作者：
Kato, Ryuichi
中科院分区：
文献类型：
--
作者：
Kudo, Norio;Kumagai, Keigo;Kato, Ryuichi
胞质蛋白CERT将神经酰胺从内质网转移到高尔基体，在那里神经酰胺转化为SM。CERT的c端START（甾体性急性调节蛋白相关脂质转移）结构域在其中心两亲性腔中结合一个神经酰胺分子。（1R,3R）- n -（3-羟基-1-羟甲基-3-苯基丙基）烷酰胺（HPA）是一种合成的神经酰胺类似物，通过CERT抑制神经酰胺的转移。本文报道了不同酰基链长的HPA配合物中CERT START结构域的晶体结构。在这些结构中，一个HPA分子被埋在两亲性腔中，其中HPA的酰胺和羟基与特定的an-亚麻酸残基形成氢键网络。Omega - 1环被认为是一个腔的门，当与HPA结合时与与神经酰胺结合时采用不同的构象。在Omega - 1环区，Trp473显示出这两种结构之间最大的差异。这种残基以hpa结合的结构存在于空腔内，而以载脂蛋白形式和神经酰胺结合的复合体结构暴露于蛋白质的外部。表面等离子体共振实验证实了Trp473在与膜的相互作用中是重要的。这些结果不仅提供了hpa抑制的分子机制，而且还提供了CERT与神经酰胺相互作用的可能机制。2009爱思唯尔有限公司版权所有。
The cytosolic protein CERT transfers ceramide from the endoplasmic reticulum to the Golgi apparatus where ceramide is converted to SM. The C-terminal START (steroidogenic acute regulatory protein-related lipid transfer) domain of CERT binds one ceramide molecule in its central amphiphilic cavity. (1R,3R)-N-(3-Hydroxy-1-hydroxymethyl-3-phenylpropyl)alkanamide (HPA), a synthesized analogue of ceramide, inhibits ceramide transfer by CERT. Here we report crystal structures of the CERT START domain in complex with HPAs of varying acyl chain lengths. In these structures, one HPA molecule is buried in the amphiphilic cavity where the amide and hydroxyl groups of HPA form a hydrogen-bond network with specific an-Lino acid residues. The Omega 1 loop, which has been suggested to function as a gate of the cavity, adopts a different conformation when bound to HPA than when bound to ceramide. In the Omega 1 loop region, Trp473 shows the largest difference between these two structures. This residue exists inside of the cavity in HPA-bound structures, while it is exposed to the outside of the protein in the apo-form and ceramide-bound complex structures. Surface plasmon resonance experiments confirmed that Trp473 is important for interaction with membranes. These results provide insights into not only the molecular mechanism of inhibition by HPAs but also possible mechanisms by which CERT interacts with ceramide. (C) 2009 Elsevier Ltd. All rights reserved.