Identification of a dominant endoplasmic reticulum-retention signal in yellow fever virus pre-membrane protein.
Yellow fever virus (YFV) encodes two envelope proteins, pre-membrane (prM) and envelope (E), that accumulate in the endoplasmic reticulum (ER). The C termini of prM and E form two antiparallel transmembrane alpha-helices that contain ER-retention signals. To understand further the ER retention of the prME heterodimer, we characterized the subcellular localization of chimeric proteins made of a reporter protein fused to the transmembrane segments of YFV envelope proteins. We showed that at least three of the transmembrane segments of the prME heterodimer are ER-retention signals. Interestingly, increasing the length of these alpha-helices led to the export of the chimeric proteins out of the ER. Furthermore, adding a diacidic export signal at the C terminus of the first transmembrane segment of the E protein also induced export to the cell surface. However, adding this export signal at the C terminus of the first transmembrane segment of E in the context of prME did not change the subcellular localization of the prME heterodimer, suggesting the presence of a stronger ER-retention signal outside the first transmembrane segment of E. Importantly, the diacidic export motif added to the C terminus of the first transmembrane segment of the prM protein was not sufficient to export a chimeric protein out of the ER, indicating that this sequence is a dominant ER-retention signal. Together, these data indicate that a combination of several signals of different strengths contributes to the ER retention of the YFV envelope protein heterodimer.
Ciczora
Yann
Y
Université Lille Nord de France, F-59000 Lille, France.
Callens
Nathalie
N
Séron
Karin
K
Rouillé
Yves
Y
Dubuisson
Jean
J
D000595:Amino Acid Sequence; D019281:Dimerization; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000821:virology*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals; D017433:Protein Structure, Secondary; D021381:Protein Transport; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015004:Yellow Fever / Q000378:metabolism / Q000821:virology*; D015005:Yellow fever virus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D021382:Protein Sorting Signals; D014759:Viral Envelope Proteins