title: Intracellular retention of duck hepatitis B virus large surface protein is independent of preS topology.
abstract: The mechanism of intracellular retention for the large surface protein (L) of duck hepatitis B virus (DHBV) was analyzed by examination of the transmembrane topologies and secretory properties of a collection of DHBV L mutants and compared with that of human hepatitis B virus (HBV) L. Our results demonstrate that, in contrast to its HBV counterpart, intracellular retention of DHBV L does not depend on the cytosolic disposition of its preS domain. L mutants with either cytosolic or lumenal preS were mostly retained in the absence of the small surface protein (S), whereas coexpression with S resulted in efficient secretion of both topological forms. Coexpression of the wild-type DHBV L with S resulted in efficient incorporation of L into secreted S + L particles, whereas HBV L was partially excluded from secreted particles under the same conditions. We propose that HBV provides L retention even in the presence of an excess of S, by exclusion of molecules with cytosolic preS domains from secreted particles at the stage of their assembly. DHBV lacks such a retention mechanism due to the absence of topological selection in particulate assembly.
authors.affiliation: Macfarlane Burnet Centre for Medical Research, Fairfield, Victoria, Australia.
authors.forename: E V
authors.initials: EV
authors.lastname: Gazina
authors.forename: B
authors.initials: B
authors.lastname: Lin
authors.forename: A
authors.initials: A
authors.lastname: Gallina
authors.forename: G
authors.initials: G
authors.lastname: Milanesi
authors.forename: D A
authors.initials: DA
authors.lastname: Anderson
mesh_terms: D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002645:Chickens; D006031:Glycosylation; D006514:Hepatitis B Surface Antigens / Q000378:metabolism*; D015611:Hepatitis B Virus, Duck / Q000378:metabolism*; D006515:Hepatitis B virus / Q000378:metabolism; D006801:Humans; D016296:Mutagenesis; D019814:Myristic Acid; D010766:Phosphorylation; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000378:metabolism*
chemical_list: D006514:Hepatitis B Surface Antigens; C096362:L protein, hepatitis B virus; D011498:Protein Precursors; D014759:Viral Envelope Proteins; C050806:presurface protein 1, hepatitis B surface antigen; C050807:presurface protein 2, hepatitis B surface antigen; D019814:Myristic Acid