摘要
Human glycerol channel aquaporin 7(AQP7)conducts glycerol release from adipocyte and enters the cells in pancreatic islets,muscles,and kidney tubules,and thus regulates glycerol metabolism in those tissues.Compared with other human aquaglyceroporins,AQP7 shows a less conserved‘‘NPA”motif in the center cavity and a pair of aromatic residues at Ar/R selectivity filter.To understand the structural basis for the glycerol conductance,we crystallized the human AQP7 and determined the structure at 3.7Å.A substrate binding pocket was found near the Ar/R filter where a glycerol molecule is bound and stabilized by R229.Glycerol uptake assay on human AQP7 as well as AQP3 and AQP10 demonstrated strong glycerol transportation activities at the physiological condition.The human AQP7 structure,in combination with the molecular dynamics simulation thereon,reveals a fully closed conformation with its permeation pathway strictly confined by the Ar/R filter at the exoplasmic side and the gate at the cytoplasmic side,and the binding of glycerol at the Ar/R filter plays a critical role in controlling the glycerol flux by driving the dislocation of the residues at narrowest parts of glycerol pathway in AQP7.
人类甘油通道AQP7催化甘油从脂肪细胞中释放并进入胰岛、肌肉和肾小管的细胞,并且由此调节这些组织中的甘油代谢.与其他人类甘油水通道相比,AQP7在其中央腔室的"NPA"基序上表现出较低的保守性,同时在Ar/R选择过滤器处具有一对芳香族残基.为了解该甘油转运的结构基础,本文结晶了人类AQP7蛋白并测定了分辨率为3.7A的结构.在Ar/R过滤器附近发现了一个底物结构口袋,其中结合有一个甘油分子,该分子通过R229残基而稳定于此.针对人类AQP7、AQP3和AQP10进行的甘油摄取测试均在生理条件下展现出有力的甘油转运活性.这一人类AQP7结构结合对其进行的分子动态模拟揭示了一个完全关闭的构象,细胞外侧的Ar/R过滤器与细胞内侧的门控对其穿透通路进行了严格的限制.通过驱动AQP7中甘油通路最狭窄部位残基的挪转,Ar/R过滤器处的甘油结合在控制甘油流动上发挥关键作用.
作者
Li Zhang
Deqiang Yao
Ying Xia
Fu Zhou
Qing Zhang
Qian Wang
An Qin
Jie Zhao
Dianfan Li
Yan Li
Lu Zhou
Yu Cao
张丽;姚德强;夏莹;周富;张庆;王倩;秦安;赵杰;李典范;李嫣;周璐;曹禹(CAS Center for Excellence on Molecular Cell Science,Institute of Biochemistry and Cell Biology,Chinese Academy of Sciences,University of Chinese Academy of Sciences,Shanghai 201210,China;Institute of Precision Medicine,The Ninth People’s Hospital,Shanghai Jiao Tong University School of Medicine,Shanghai 200125,China;iHuman Institute,ShanghaiTech University,Shanghai 201210,China;Department of Orthopaedics,Shanghai Key Laboratory of Orthopaedic Implant,Shanghai Ninth People’s Hospital,Shanghai Jiao Tong University School of Medicine,Shanghai 200011,China;Department of Medicinal Chemistry,School of Pharmacy,Fudan University,Shanghai 200433,China)
基金
the National Key Research and Development Program of China(2018YFC1004704 and 2017YFC1001303)
the National Natural Science Foundation of China(U1632132,31670849,and 91853206)
the Shanghai Science and Technology Committee(20S11902000)
the SHIPM-pi fund(JY201804)
the SHIPM-sigma fund(2018JC002)from Shanghai Institute of Precision Medicine,Ninth People’s Hospital Shanghai Jiao Tong University School of Medicine
the Innovative Research Team of Highlevel Local Universities in Shanghai(SSMU-ZLCX20180600)。
