Topological changes in the transmembrane domains of hepatitis C virus envelope glycoproteins.
Hepatitis C virus proteins are synthesized as a polyprotein cleaved by a signal peptidase and viral proteases. The behaviour of internal signal sequences at the C-terminus of the transmembrane domains of hepatitis C virus envelope proteins E1 and E2 is essential for the topology of downstream polypeptides. We determined the topology of these transmembrane domains before and after signal sequence cleavage by tagging E1 and E2 with epitopes and by analysing their accessibility in selectively permeabilized cells. We showed that, after cleavage by signal peptidase in the endoplasmic reticulum, the C-terminal orientation of these transmembrane domains changed from luminal to cytosolic. The dynamic behaviour of these transmembrane domains is unique and it is linked to their multifunctionality. By reorienting their C-terminus toward the cytosol and being part of a transmembrane domain, the signal sequences at the C-terminus of E1 and E2 contribute to new functions: (i) membrane anchoring; (ii) E1E2 heterodimerization; and (iii) endoplasmic reticulum retention.
Cocquerel
Laurence
L
CNRS-UPR2511, Institut de Biologie de Lille and Institut Pasteur de Lille, 1 rue Calmette, BP447, 59021 Lille Cedex, France.
Op de Beeck
Anne
A
Lambot
Michel
M
Roussel
Juliette
J
Delgrange
David
D
Pillez
André
A
Wychowski
Czeslaw
C
Penin
François
F
Dubuisson
Jean
J
D000595:Amino Acid Sequence; D002460:Cell Line; D019281:Dimerization; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016174:Hepacivirus / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
C087035:E1 protein, Hepatitis C virus; D000939:Epitopes; D021382:Protein Sorting Signals; D014759:Viral Envelope Proteins; C091015:glycoprotein E2, Hepatitis C virus