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研究解析人类ACAT1四聚体结构
2020-05-14 23:55

美国德克萨斯大学西南医学中心李晓淳研究组解析了nevanimibe结合下的人类ACAT1四聚体结构。2020年5月13日,《自然》杂志在线发表了这项成果。

研究人员报道了与nevanimibe结合的人源ACAT1冷冻电镜结构。nevanimibe是一种抑制剂,目前正在临床试验中用于治疗先天性肾上腺皮质增生。ACAT1全酶是由两个同源二聚体组成的四聚体。每个单体包含9个跨膜螺旋(TM),其中6个(TM4-TM9)形成一个腔,可容纳nevanimibe和内源性酰基辅酶A。该腔还包含一个以前被确定为催化活性必不可少的组氨酸。这些结构数据和生化分析提供了一个物理模型来解释胆固醇酯化的过程,以及nevanimibe和ACAT1之间相互作用的详细信息,这可能有助于加速开发ACAT1抑制剂来治疗相关疾病。
 
据了解,胆固醇是哺乳动物细胞膜的重要组成部分,占血浆膜脂质的50%。相比之下,它仅占内质网(ER)中脂质的5%。ER酶固醇O-酰基转移酶1(也称为酰基辅酶A:胆固醇酰基转移酶,ACAT1)将长链脂肪酸转移至胆固醇,形成胆固醇酯,后者聚结成胞质脂质滴。在胆固醇超负荷的情况下,ACAT1维持ER的低胆固醇浓度,因此在胆固醇稳态中起着至关重要的作用。ACAT1也与阿尔茨海默氏病、动脉粥样硬化和癌症有关。
 
附:英文原文

Title: Structure of nevanimibe-bound tetrameric human ACAT1

Author: Tao Long, Yingyuan Sun, Abdirahman Hassan, Xiaofeng Qi, Xiaochun Li

Issue&Volume: 2020-05-13

Abstract: Cholesterol is an essential component of mammalian cell membranes, constituting up to 50% of plasma membrane lipids. By contrast, it accounts for only 5% of lipids in the endoplasmic reticulum (ER)1. The ER enzyme sterol O-acyltransferase 1 (also named acyl-coenzyme A:cholesterol acyltransferase, ACAT1) transfers a long-chain fatty acid to cholesterol to form cholesteryl esters that coalesce into cytosolic lipid droplets. Under conditions of cholesterol overload, ACAT1 maintains the low cholesterol concentration of the ER and thereby has an essential role in cholesterol homeostasis2,3. ACAT1 has also been implicated in Alzheimer’s disease4, atherosclerosis5 and cancers6. Here we report a cryo-electron microscopy structure of human ACAT1 in complex with nevanimibe7, an inhibitor that is in clinical trials for the treatment of congenital adrenal hyperplasia. The ACAT1 holoenzyme is a tetramer that consists of two homodimers. Each monomer contains nine transmembrane helices (TMs), six of which (TM4–TM9) form a cavity that accommodates nevanimibe and an endogenous acyl-coenzyme A. This cavity also contains a histidine that has previously been identified as essential for catalytic activity8. Our structural data and biochemical analyses provide a physical model to explain the process of cholesterol esterification, as well as details of the interaction between nevanimibe and ACAT1, which may help to accelerate the development of ACAT1 inhibitors to treat related diseases.

DOI: 10.1038/s41586-020-2295-8

Source: https://www.nature.com/articles/s41586-020-2295-8

Nature:《自然》,创刊于1869年。隶属于施普林格·自然出版集团,最新IF:69.504
官方网址:http://www.nature.com/
投稿链接:http://www.nature.com/authors/submit_manuscript.html


本期文章:《自然》:Online/在线发表

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