title: Characterization of the human cytomegalovirus gH/gL/UL128-131 complex that mediates entry into epithelial and endothelial cells.
abstract: The entry of human cytomegalovirus (HCMV) into biologically relevant epithelial and endothelial cells involves endocytosis followed by low-pH-dependent fusion. This entry pathway is facilitated by the HCMV UL128, UL130, and UL131 proteins, which form one or more complexes with the virion envelope glycoprotein gH/gL. gH/gL/UL128-131 complexes appear to be distinct from the gH/gL/gO complex, which likely facilitates entry into fibroblasts. In order to better understand the assembly and protein-protein interactions of gH/gL/UL128-131 complexes, we generated HCMV mutants lacking UL128-131 proteins and nonreplicating adenovirus vectors expressing gH, gL, UL128, UL130, and UL131. Our results demonstrate that UL128, UL130, and UL131 can each independently assemble onto gH/gL scaffolds. However, the binding of individual UL128-131 proteins onto gH/gL can significantly affect the binding of other proteins; for example, UL128 increased the binding of both UL130 and UL131 to gH/gL. Direct interactions between gH/UL130, UL130/UL131, gL/UL128, and UL128/UL130 were also observed. The export of gH/gL complexes from the endoplasmic reticulum (ER) to the Golgi apparatus and cell surface was dramatically increased when all of UL128, UL130, and UL131 were coexpressed with gH/gL (with or without gO expression). Incorporation of gH/gL complexes into the virion envelope requires transport beyond the ER. Thus, we concluded that UL128, UL130, and UL131 must all bind simultaneously onto gH/gL for the production of complexes that can function in entry into epithelial and endothelial cells.
authors.affiliation: 6366 Basic Sciences Building, Mail Code L-220, Department of Molecular Microbiology and Immunology, Oregon Health and Sciences University, 3181 Sam Jackson Park Rd., Portland, OR 97239, USA. ryckmanb@ohsu.edu
authors.forename: Brent J
authors.initials: BJ
authors.lastname: Ryckman
authors.forename: Barb L
authors.initials: BL
authors.lastname: Rainish
authors.forename: Marie C
authors.initials: MC
authors.lastname: Chase
authors.forename: Jamie A
authors.initials: JA
authors.lastname: Borton
authors.forename: Jay A
authors.initials: JA
authors.lastname: Nelson
authors.forename: Michael A
authors.initials: MA
authors.lastname: Jarvis
authors.forename: David C
authors.initials: DC
authors.lastname: Johnson
mesh_terms: D002462:Cell Membrane / Q000737:chemistry; D003587:Cytomegalovirus / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000737:chemistry; D042783:Endothelial Cells / Q000821:virology*; D004847:Epithelial Cells / Q000821:virology*; D006056:Golgi Apparatus / Q000737:chemistry; D006801:Humans; D011485:Protein Binding; D021381:Protein Transport; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D053586:Virus Internalization
chemical_list: D014764:Viral Proteins