title: Biochemical and structural characterization of the capsid-bound tegument proteins of human cytomegalovirus.
abstract: Human cytomegalovirus (HCMV) is the most genetically and structurally complex human herpesvirus and is composed of an envelope, a tegument, and a dsDNA-containing capsid. HCMV tegument plays essential roles in HCMV infection and assembly. Using cryo electron tomography (cryoET), here we show that HCMV tegument compartment can be divided into two sub-compartments: an inner and an outer tegument. The inner tegument consists of densely-packed proteins surrounding the capsid. The outer tegument contains those components that are loosely packed in the space between the inner tegument and the pleomorphic glycoprotein-containing envelope. To systematically characterize the inner tegument proteins interacting with the capsid, we used chemical treatment to strip off the entire envelope and most tegument proteins to obtain a tegumented capsid with inner tegument proteins. SDS-polyacrylamide gel electrophoresis analyses show that only two tegument proteins, UL32-encoded pp150 and UL48-encoded high molecular weight protein (HMWP), remains unchanged in their abundance in the tegumented capsids as compared to their abundance in the intact particles. Three-dimensional reconstructions by single particle cryo electron microscopy (cryoEM) reveal that the net-like layer of icosahedrally-ordered tegument densities are also the same in the tegumented capsid and in the intact particles. CryoET reconstruction of the tegumented capsid labeled with an anti-pp150 antibody is consistent with the biochemical and cryoEM data in localizing pp150 within the ordered tegument. Taken together, these results suggest that pp150, a betaherpesvirus-specific tegument protein, is a constituent of the net-like layer of icosahedrally-ordered capsid-bound tegument densities, a structure lacking similarities in alpha and gammaherpesviruses.
authors: Department of Microbiology, Immunology and Molecular Genetics, University of California at Los Angeles, USA.
authors: Xuekui
authors: X
authors: Yu
authors: Sanket
authors: S
authors: Shah
authors: Manfred
authors: M
authors: Lee
authors: Wei
authors: W
authors: Dai
authors: Pierrette
authors: P
authors: Lo
authors: William
authors: W
authors: Britt
authors: Hua
authors: H
authors: Zhu
authors: Fenyong
authors: F
authors: Liu
authors: Z Hong
authors: ZH
authors: Zhou
mesh_terms: D002213:Capsid / Q000737:chemistry* / Q000648:ultrastructure*; D036022:Capsid Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D002478:Cells, Cultured; D020285:Cryoelectron Microscopy / Q000379:methods; D003587:Cytomegalovirus / Q000737:chemistry* / Q000648:ultrastructure*; D055032:Electron Microscope Tomography / Q000379:methods; D006801:Humans; D008958:Models, Molecular; D011487:Protein Conformation
chemical_list: D036022:Capsid Proteins