title: Four levels of hierarchical organization, including noncovalent chainmail, brace the mature tumor herpesvirus capsid against pressurization.
abstract: Like many double-stranded DNA viruses, tumor gammaherpesviruses Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus withstand high internal pressure. Bacteriophage HK97 uses covalent chainmail for this purpose, but how this is achieved noncovalently in the much larger gammaherpesvirus capsid is unknown. Our cryoelectron microscopy structure of a gammaherpesvirus capsid reveals a hierarchy of four levels of organization: (1) Within a hexon capsomer, each monomer of the major capsid protein (MCP), 1,378 amino acids and six domains, interacts with its neighboring MCPs at four sites. (2) Neighboring capsomers are linked in pairs by MCP dimerization domains and in groups of three by heterotrimeric triplex proteins. (3) Small (∼280 amino acids) HK97-like domains in MCP monomers alternate with triplex heterotrimers to form a belt that encircles each capsomer. (4) One hundred sixty-two belts concatenate to form noncovalent chainmail. The triplex heterotrimer orchestrates all four levels and likely drives maturation to an angular capsid that can withstand pressurization.
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095-7364, USA; California NanoSystems Institute, UCLA, Los Angeles, CA 90095-7151, USA; Department of Pathology and Laboratory Medicine, The University of Texas Medical School at Houston, Houston, TX 77030, USA. Electronic address: hong.zhou@ucla.edu.
authors.forename: Z Hong
authors.initials: ZH
authors.lastname: Zhou
authors.affiliation: California NanoSystems Institute, UCLA, Los Angeles, CA 90095-7151, USA; Department of Pathology and Laboratory Medicine, The University of Texas Medical School at Houston, Houston, TX 77030, USA.
authors.forename: Wong Hoi
authors.initials: WH
authors.lastname: Hui
authors.affiliation: Department of Pathology and Laboratory Medicine, The University of Texas Medical School at Houston, Houston, TX 77030, USA.
authors.forename: Sanket
authors.initials: S
authors.lastname: Shah
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095-7364, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Jih
authors.affiliation: Department of Molecular Genetics, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Christine M
authors.initials: CM
authors.lastname: O'Connor
authors.affiliation: Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Sherman
authors.affiliation: Department of Microbiology, Immunology and Cancer Biology, Myles H. Thaler Center for AIDS and Human Retrovirus Research, University of Virginia, Charlottesville, VA 22908, USA; Department of Medicine, University of Virginia, Charlottesville, VA 22908, USA.
authors.forename: Dean H
authors.initials: DH
authors.lastname: Kedes
authors.affiliation: California NanoSystems Institute, UCLA, Los Angeles, CA 90095-7151, USA; Department of Psychology, UCLA, Los Angeles, CA 90095-1563, USA.
authors.forename: Stan
authors.initials: S
authors.lastname: Schein
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002213:Capsid / Q000737:chemistry*; D036022:Capsid Proteins / Q000737:chemistry*; D020285:Cryoelectron Microscopy; D019281:Dimerization; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D018144:Rhadinovirus / Q000737:chemistry*
chemical_list: D036022:Capsid Proteins