title: Open reading frame III of borna disease virus encodes a nonglycosylated matrix protein.
abstract: The open reading frame III of Borna disease virus (BDV) codes for a protein with a mass of 16 kDa, named p16 or BDV-M. p16 was described as an N-glycosylated protein in several previous publications and therefore was termed gp18, although the amino acid sequence of p16 does not contain any regular consensus sequence for N glycosylation. We examined glycosylation of p16 and studied its membrane topology using antisera raised against peptides, which comprise the N and the C termini. Neither an N- nor a C-terminal peptide is cleaved from p16 during maturation. Neither deglycosylation of p16 by endoglycosidases nor binding of lectin to p16 was detectable. Introduction of typical N-glycosylation sites at the proposed sites of p16 failed in carbohydrate attachment. Flotation experiments with membranes of BDV-infected cells on density gradients revealed that p16 is not an integral membrane protein, since it can be dissociated from membranes. Our experimental data strongly suggest that p16 is a typical nonglycosylated matrix protein associated at the inner surface of the viral membrane, as is true for homologous proteins of other members of the Mononegavirales order.
authors.affiliation: Institut für Virologie, Philipps-Universität Marburg, D-35037 Marburg, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Kraus
authors.forename: M
authors.initials: M
authors.lastname: Eickmann
authors.forename: S
authors.initials: S
authors.lastname: Kiermayer
authors.forename: H
authors.initials: H
authors.lastname: Scheffczik
authors.forename: M
authors.initials: M
authors.lastname: Fluess
authors.forename: J A
authors.initials: JA
authors.lastname: Richt
authors.forename: W
authors.initials: W
authors.lastname: Garten
mesh_terms: D001287:Attachment Sites, Microbiological; D001891:Borna disease virus / Q000737:chemistry / Q000235:genetics*; D002241:Carbohydrates / Q000032:analysis; D002462:Cell Membrane / Q000737:chemistry; D006031:Glycosylation; D057927:Hydrophobic and Hydrophilic Interactions; D016366:Open Reading Frames; D014763:Viral Matrix Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics
chemical_list: D002241:Carbohydrates; D014763:Viral Matrix Proteins