权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Structural basis of the neutral sphingomyelinase to understand the lipid raft

中性鞘磷脂酶的结构基础了解脂筏

基本信息

批准号：
17590256
负责人：
TSUGE Hideaki
金额：
$ 2.3万
依托单位：
Tokushima Bunri University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

Sphingomyelinase (SMase) from Bacillus cereus (Bc-SMase) hydrolyzes sphingomyelin to phosphocholine and ceramide in a divalent metal ion-dependent manner. Bc-SMase is a homologue of mammalian neutral SMase (nSMase) and mimics the actions of the endogenous mammalian nSMase in causing differentiation, development, aging, and apoptosis. Thus Bc-SMase may be a good model for the poorly characterized mammalian nSMase. The metal ion activation of sphingomyelinase activity of Bc-SMase was in the order Co2+ > or = Mn2+ > or = Mg2+ >> Ca2+ > or = Sr2+. The first crystal structures of Bc-SMase bound to Co2+, Mg2+, or Ca2+ were determined. The water-bridged double divalent metal ions at the center of the cleft in both the Co2+-and Mg2+-bound forms were concluded to be the catalytic architecture required for sphingomyelinase activity. In contrast, the architecture of Ca2+ binding at the site showed only one binding site. A further single metal-binding site exists at one side edge of the cleft. Based on the highly conserved nature of the residues of the binding sites, the crystal structure of Bc-SMase with bound Mg2+ or Co2+ may provide a common structural framework applicable to phosphohydrolases belonging to the DNase I-like folding superfamily. In addition, the structural features and site-directed mutagenesis suggest that the specific beta-hairpin with the aromatic amino acid residues participates in binding to the membrane-bound sphingomyelin substrate.

来自蜡状芽孢杆菌的鞘磷脂酶（Bc-SMase）以二价金属离子依赖的方式将鞘磷脂水解为磷酸胆碱和神经酰胺。Bc-SMase是哺乳动物中性SMase（nSMase）的同源物，并且模拟内源性哺乳动物nSMase在引起分化、发育、老化和凋亡中的作用。因此，Bc-SMase可能是一个很好的模型，为穷人的特点哺乳动物nSMase。金属离子对Bc-SMase鞘磷脂酶活性的激活作用顺序为Co ~（2+）>或= Mn ~（2+）>或= Mg ~（2+）>> Ca ~（2+）>或= Sr ~（2+）。测定了与Co ~（2+）、Mg ~（2+）或Ca ~（2+）结合的Bc-SMase的一级晶体结构。水桥接的双二价金属离子在两个Co2+-和Mg 2 +-结合形式的裂缝中心的结论是鞘磷脂酶活性所需的催化架构。与此相反，在该网站的Ca 2+结合的架构显示只有一个结合位点。另一个单一的金属结合位点存在于裂缝的一侧边缘。基于结合位点残基的高度保守性质，具有结合的Mg 2+或Co 2+的Bc-SMase的晶体结构可以提供适用于属于DNase I样折叠超家族的磷酸水解酶的共同结构框架。此外，结构特征和定点突变表明，具有芳香族氨基酸残基的特异性β-发夹参与与膜结合鞘磷脂底物的结合。