title: Intracellular processing of human herpesvirus 6 glycoproteins Q1 and Q2 into tetrameric complexes expressed on the viral envelope.
abstract: Human herpesvirus 6 (HHV-6) glycoproteins H and L (gH and gL, respectively) and the 80-kDa form of glycoprotein Q (gQ-80K) form a heterotrimeric complex that is found on the viral envelope and that is a viral ligand for human CD46. Besides gQ-80K, the gQ gene encodes an additional product whose mature molecular mass is 37 kDa (gQ-37K) and which is derived from a different transcript. Therefore, we designated gQ-80K as gQ1 and gQ-37K as gQ2. We show here that gQ2 also interacts with the gH-gL-gQ1 complex in HHV-6-infected cells and in virions. To examine how these components interact in HHV-6-infected cells, we performed pulse-chase studies. The results demonstrated that gQ2-34K, which is endo-beta-N-acetylglucosaminidase H sensitive and which is the precursor form of gQ2-37K, associates with gQ1-74K, which is the precursor form of gQ1-80K, within 30 min of the pulse period. After a 1-h chase, these precursor forms had associated with the gH-gL dimer. Interestingly, an anti-gH monoclonal antibody coimmunoprecipitated mainly gQ1-80K and gQ2-37K, with little gQ1-74K or gQ2-34K. These results indicate that although gQ2-34K and gQ1-74K interact in the endoplasmic reticulum, the gH-gL-gQ1-80K-gQ2-37K heterotetrameric complex arises in the post-endoplasmic reticulum compartment. The mature complex is subsequently incorporated into viral particles.
authors.affiliation: Department of Microbiology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan.
authors.forename: Pilailuk
authors.initials: P
authors.lastname: Akkapaiboon
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Mori
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Sadaoka
authors.forename: Sayoko
authors.initials: S
authors.lastname: Yonemoto
authors.forename: Koichi
authors.initials: K
authors.lastname: Yamanishi
mesh_terms: D000595:Amino Acid Sequence; D002460:Cell Line; D006023:Glycoproteins / Q000737:chemistry*; D015654:Herpesvirus 6, Human / Q000737:chemistry*; D006801:Humans; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D014158:Transcription, Genetic; D014759:Viral Envelope Proteins / Q000737:chemistry*; D014771:Virion / Q000737:chemistry
chemical_list: D006023:Glycoproteins; D014759:Viral Envelope Proteins