The role of single N-glycans in proteolytic processing and cell surface transport of the Lassa virus glycoprotein GP-C.
Lassa virus glycoprotein is synthesised as a precursor (preGP-C) into the lumen of the endoplasmic reticulum. After cotranslational cleavage of the signal peptide, the immature GP-C is posttranslationally processed into the N-terminal subunit GP-1 and the C-terminal subunit GP-2 by the host cell subtilase SKI-1/S1P. The glycoprotein precursor contains eleven potential N-glycosylation sites. In this report, we investigated the effect of each N-glycan on proteolytic cleavage and cell surface transport by disrupting the consensus sequences of eleven potential N-glycan attachment sites individually. Five glycoprotein mutants with disrupted N-glycosylation sites were still proteolytically processed, whereas the remaining N-glycosylation sites are necessary for GP-C cleavage. Despite the lack of proteolytic processing, all cleavage-defective mutants were transported to the cell surface and remained completely endo H-sensitive. The findings indicate that N-glycans are needed for correct conformation of GP-C in order to be cleaved by SKI-1/S1P.
Eichler
Robert
R
Institut für Virologie der Philipps-Universität Marburg, Hans-Meerwein-Str, 3, 35037 Marburg, Germany. Robert.Eichler@abbott.com
Lenz
Oliver
O
Garten
Wolfgang
W
Strecker
Thomas
T
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D006031:Glycosylation; D007836:Lassa virus / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011134:Polysaccharides / Q000378:metabolism*; D043484:Proprotein Convertases / Q000378:metabolism; D011487:Protein Conformation; D017510:Protein Folding; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D014162:Transfection; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D006023:Glycoproteins; D011134:Polysaccharides; D011498:Protein Precursors; D014759:Viral Envelope Proteins; C066508:glycoprotein gp1, lassa virus; C077198:glycoprotein gp2, lassa virus; D043484:Proprotein Convertases; D012697:Serine Endopeptidases; C115575:membrane-bound transcription factor peptidase, site 1