title: HCMV gB shares structural and functional properties with gB proteins from other herpesviruses.
abstract: Glycoprotein B (gB) facilitates HCMV entry into cells by binding receptors and mediating membrane fusion. The crystal structures of gB ectodomains from HSV-1 and EBV are available, but little is known about the HCMV gB structure. Using multiangle light scattering and electron microscopy, we show here that HCMV gB ectodomain is a trimer with the overall shape similar to HSV-1 and EBV gB ectodomains. HCMV gB ectodomain forms rosettes similar to rosettes formed by EBV gB and the postfusion forms of other viral fusogens. Substitution of several bulky hydrophobic residues within the putative fusion loops with more hydrophilic residues reduced rosette formation and abolished cell fusion. We propose that like gB proteins from HSV-1 and EBV, HCMV gB has two internal hydrophobic fusion loops that likely interact with target membranes. Our work establishes structural and functional similarities between gB proteins from three subfamilies of herpesviruses.
authors.affiliation: Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA.
authors.forename: Sapna
authors.initials: S
authors.lastname: Sharma
authors.forename: Todd W
authors.initials: TW
authors.lastname: Wisner
authors.forename: David C
authors.initials: DC
authors.lastname: Johnson
authors.forename: Ekaterina E
authors.initials: EE
authors.lastname: Heldwein
mesh_terms: D000595:Amino Acid Sequence; D003587:Cytomegalovirus / Q000235:genetics / Q000378:metabolism; D006564:Herpesviridae / Q000235:genetics / Q000378:metabolism; D018259:Herpesvirus 1, Human / Q000235:genetics / Q000378:metabolism; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000378:metabolism; D013058:Mass Spectrometry; D008561:Membrane Fusion; D008854:Microscopy, Electron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D014759:Viral Envelope Proteins; C040495:glycoprotein B, Simplexvirus