Comparative cellular processing of the human immunodeficiency virus (HIV-1) envelope glycoprotein gp160 by the mammalian subtilisin/kexin-like convertases.
We present here the pulse and pulse-chase analysis of the biosynthesis of the envelope glycoprotein gp160 and its intracellular processing by the subtilisin/kexin-like convertases furin, PACE4, PC1, PC5 and its isoform PC5/6-B. We demonstrate that furin and to a much lesser extent PACE4, PC5/6-B and PC1 are candidate enzymes capable of processing gp160 intracellularly. Furthermore we show that furin can also process gp160/gp120 into gp77/gp53 products by cleavage at the sequence RIQR/GPGR just preceding the conserved GPGR structure found at the tip of the hypervariable V3 loop. The results show that processing into gp120 could occur at or before the trans-Golgi network (TGN) where sulphation of the oligosaccharide moieties of gp160 was detected. In contrast, the formation of gp77/gp53 by furin is a late event occurring after exit from the TGN. Our data also revealed that the alpha glucosidase I inhibitor N-butyldeoxynojirimycin, although affecting the oligosaccharide composition of gp160, does not impair the processing of either gp160 or gp120 by either furin or PACE4. Finally, the co-expression of the [Arg355, Arg358]-alpha-1-antitrypsin Portland variant was shown to potently inhibit the processing of both gp160 and gp120 by these convertases.
Vollenweider
F
F
J.A. DeSève Laboratories of Biochemical and Molecular Neuroendocrinology, Montréal, Québec, Canada.
Benjannet
S
S
Decroly
E
E
Savaria
D
D
Lazure
C
C
Thomas
G
G
Chrétien
M
M
Seidah
N G
NG
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002522:Chlorocebus aethiops; D015686:Gene Products, env / Q000378:metabolism*; D006031:Glycosylation; D015699:HIV Envelope Protein gp120 / Q000378:metabolism; D019302:HIV Envelope Protein gp160; D006801:Humans; D051379:Mice; D009844:Oligosaccharides / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D013381:Subtilisins / Q000378:metabolism*; D000515:alpha 1-Antitrypsin / Q000494:pharmacology
D015686:Gene Products, env; D015699:HIV Envelope Protein gp120; D019302:HIV Envelope Protein gp160; D009844:Oligosaccharides; D011498:Protein Precursors; D000515:alpha 1-Antitrypsin; D013381:Subtilisins; D002118:Calcium