Hepadnavirus envelope topology: insertion of a loop region in the membrane and role of S in L protein translocation.
A unique feature of the large hepadnavirus envelope protein (L) is its mixed transmembrane topology, resulting from partial posttranslational translocation of the pre-S domain. Using protease protection analysis, we demonstrate for duck hepatitis B virus an essential role for the small envelope protein (S) in this process, providing the first experimental evidence for an S translocation channel. Further analysis revealed that the presumed cytoplasmic loop between TM1 and TM2 in the C-terminal S domain is membrane embedded and protrudes to the particle surface. These data suggest that some L molecules form a highly folded, potentially spring-loaded topology with five membrane-spanning regions and a membrane-traversing pre-S chain.
Grgacic
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Macfarlane Burnet Centre for Medical Research, Fairfield, Victoria, Australia. grgacic@burnet.edu.au
Kuhn
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Schaller
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H
D015153:Blotting, Western; D002478:Cells, Cultured; D015613:Hepadnaviridae / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D011487:Protein Conformation; D014162:Transfection; D014759:Viral Envelope Proteins / Q000032:analysis / Q000737:chemistry* / Q000235:genetics
D014759:Viral Envelope Proteins