Molecular mechanisms of hollow nano-particle formation by a viral envelope protein

病毒包膜蛋白形成中空纳米颗粒的分子机制

基本信息

批准号：
17500306
负责人：
TADA Hiroko
金额：
$ 1.92万
依托单位：
OKAYAMA 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

Virus-like hollow nano-particles in a diameter of 50・500nm are formed when envelope protein of human hepatitis B virus (HBV), which is also referred as surface antigen of HBV (HBsAg), is expressed in animal cells and yeast cells. The expressed protein aggregates on the endoplasmic reticulum (ER) membrane first and then buds out into the lumen as particles containing lipid bilayer derived from ER. In this study, we tried to clarify the molecular mechanisms of this nano-particle structure formation by HBsAg.(1) We constructed several deletion mutants of HBsAg and evaluated their abilities of nano-particle formation, to clarify the essential and/or the unnecessary sequences for particle formation. As the results, among 226 amino acid-residues of HBsAg protein, 54 residues in C-terminal hydrophobic region of 71 residues, 50 residues hydrophilic particle-surface hydrophilic region of 57 residues, and 44 residues in inner-particle hydrophilic region of 50 residues could be deleted from HBsAg sequence without significant loss of particle secretion (more than 50% of wild type HBsAg). C-terminal 54 residues and particle-surface 50 residues (total 104 residues) and C-terminal 54 residues and inner particle 44 residues (total 98 residues) could be also deleted simultaneously without significant loss of particle secretion. These results indicated that these delete-capable sequences are unnecessary for particle formation. At the same time, 18-residue sequence at N-terminal of C-terminal hydrophobic region is defined to be the essential sequence for particle formation.2) The 18-residue essential-sequence was further evaluated by introducing several mutations into this site. The results of the mutational analysis suggest that this region form amphipathic helix lying on the interface of lipid bilayer. The amphipathic helix may have important role for two required properties for particle formation: promoting self-aggregation of HBsAg on ER membrane and generating curvature.

直径为50 nm的500nm竞争蛋白Birus（HBV）表面抗原（HBSAG）的病毒样纳米粒子在动物细胞和年细胞中表达。在本研究中，我们试图通过HBSAG（1）构建HBSAG的纳米粒子结构的分子机制结果，在HBSAG蛋白的226个氨基酸分散中，在71个残基的c末端疏水区中有54个残基在57个残基的亲水性颗粒表面亲水性区域，可从HBSAG序列中删除50个残基的44个残基，可用于50个残基的粒子亲水性调节。粒子分泌的显着丧失（超过50％的野生型HBSAG）。是不必要的强度形成。脂质双层的两亲性螺旋。