Hepatitis E virus capsid protein assembles in 4M urea in the presence of salts. (17th January 2013)

• Record Type: Journal Article
• Authors: Yang, Chunyan; Pan, Huirong; Wei, Minxi; Zhang, Xiao; Wang, Nan; Gu, Ying; Du, Hailian; Zhang, Jun; Li, Shaowei; Xia, Ningshao
• Is Part Of: Protein science. Volume 22:Number 3(2013:Mar.)
• Page Start: 314
• Page End: 326
• Publication Date: 2013-01-17
• Subjects: particle assembly -- urea -- salt -- hydrophobic interaction -- hepatitis E virus -- capsid protein; Proteins -- Periodicals; 572.6
• DOI: 10.1002/pro.2213
• Languages: English
• ISSNs: 0961-8368

Abstract

Abstract: The hepatitis E virus (HEV) capsid protein has been demonstrated to be able to assemble into particles in vitro . However, this process and the mechanism of protein–protein interactions during particle assembly remain unclear. In this study, we investigated the assembly mechanism of HEV structural protein subunits, the capsid protein p239 (aa368–606), using analytical ultracentrifugation. It was the first to observe that the p239 can form particles in 4 M urea as a result of supplementation with salt, including ammonium sulfate [(NH4 )2 SO4 ], sodium sulfate (Na2 SO4 ), sodium chloride (NaCl), and ammonium chloride (NH4 Cl). Interestingly, it is the ionic strength that determines the efficiency of promoting particle assembly. The assembly rate was affected by temperature and salt concentration. When (NH4 )2 SO4 was used, assembling intermediates of p239 with sedimentation coefficient values of approximately 5 S, which were mostly dodecamers, were identified for the first time. A highly conserved 28‐aa region (aa368–395) of p239 was found to be critical for particle assembly, and the hydrophobic residues Leu 372, Leu 375, and Leu 395 of p239 was found to be critical for particle assembly, which was revealed by site‐directed mutagenesis. This study provides new insights into the assembly mechanism of native HEV, and contributes a valuable basis for further investigations of protein assembly by hydrophobic interactions under denaturing conditions.