title: Clustering and mobility of HIV-1 Env at viral assembly sites predict its propensity to induce cell-cell fusion.
abstract: HIV-1 Env mediates virus attachment to and fusion with target cell membranes, and yet, while Env is still situated at the plasma membrane of the producer cell and before its incorporation into newly formed particles, Env already interacts with the viral receptor CD4 on target cells, thus enabling the formation of transient cell contacts that facilitate the transmission of viral particles. During this first encounter with the receptor, Env must not induce membrane fusion, as this would prevent the producer cell and the target cell from separating upon virus transmission, but how Env's fusion activity is controlled remains unclear. To gain a better understanding of the Env regulation that precedes viral transmission, we examined the nanoscale organization of Env at the surface of producer cells. Utilizing superresolution microscopy (stochastic optical reconstruction microscopy [STORM]) and fluorescence recovery after photobleaching (FRAP), we quantitatively assessed the clustering and dynamics of Env upon its arrival at the plasma membrane. We found that Gag assembly induced the aggregation of small Env clusters into larger domains and that these domains were completely immobile. Truncation of the cytoplasmic tail (CT) of Env abrogated Gag's ability to induce Env clustering and restored Env mobility at assembly sites, both of which correlated with increased Env-induced fusion of infected and uninfected cells. Hence, while Env trapping by Gag secures Env incorporation into viral particles, Env clustering and its sequestration at assembly sites likely also leads to the repression of its fusion function, and thus, by preventing the formation of syncytia, Gag helps to secure efficient transfer of viral particles to target cells.
authors: Graduate Program in Cell and Molecular Biology, University of Vermont, Burlington, Vermont, USA.
authors: Nathan H
authors: NH
authors: Roy
authors: Jany
authors: J
authors: Chan
authors: Marie
authors: M
authors: Lambelé
authors: Markus
authors: M
authors: Thali
mesh_terms: D000704:Analysis of Variance; D002459:Cell Fusion; D036681:Fluorescence Recovery After Photobleaching; D015683:Gene Products, gag / Q000378:metabolism; D015699:HIV Envelope Protein gp120 / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008853:Microscopy / Q000379:methods; D019065:Virus Assembly / Q000502:physiology*; D053585:Virus Attachment; D053586:Virus Internalization
chemical_list: D015683:Gene Products, gag; D015699:HIV Envelope Protein gp120; C514793:gp120 protein, Human immunodeficiency virus 1
references: Biophys J. 1983 Jan;41(1):95-7
references: 6824758
references: J Virol. 1994 Mar;68(3):1689-96
references: 8107229
references: J Virol. 1999 Feb;73(2):1350-61
references: 9882340
references: PLoS One. 2011;6(7):e22007
references: 21799764
references: Nat Methods. 2011 Sep 18;8(11):969-75
references: 21926998
references: J Mol Biol. 2011 Jul 22;410(4):582-608
references: 21762802
references: J Virol. 2002 Jun;76(11):5315-25
references: 11991960
references: Science. 2003 May 23;300(5623):1295-7
references: 12730499
references: EMBO J. 1998 May 1;17(9):2699-708
references: 9564051
references: J Virol. 2009 May;83(9):4060-7
references: 19224995
references: Proc Natl Acad Sci U S A. 2009 Nov 10;106(45):19114-9
references: 19861549
references: Virol J. 2012 May 02;9:84
references: 22551453
references: J Exp Med. 2004 Jan 19;199(2):283-93
references: 14734528
references: J Virol. 1996 Jan;70(1):341-51
references: 8523546
references: J Virol. 2000 Apr;74(8):3548-54
references: 10729129
references: Curr Opin Virol. 2013 Feb;3(1):44-50
references: 23219376
references: PLoS One. 2012;7(2):e31457
references: 22384026
references: PLoS Pathog. 2007 May 4;3(5):e63
references: 17480119
references: J Virol. 2005 Feb;79(4):2097-107
references: 15681412
references: Cell. 1994 Aug 12;78(3):373-87
references: 7914835
references: J Virol. 2002 Mar;76(6):2683-91
references: 11861835
references: J Virol. 2012 Feb;86(4):2347-59
references: 22156517
references: Virus Res. 2009 Aug;143(2):162-76
references: 19383519
references: Proc Natl Acad Sci U S A. 2005 Oct 25;102(43):15453-8
references: 16230638
references: Nature. 2011 Oct 23;479(7374):552-5
references: 22020284
references: PLoS Pathog. 2011 Sep;7(9):e1002234
references: 21931551
references: J Virol. 2007 Nov;81(22):12596-607
references: 17728233
references: AIDS Res Hum Retroviruses. 2011 Mar;27(3):239-47
references: 21247353
references: Proc Natl Acad Sci U S A. 2012 May 29;109(22):8564-9
references: 22586087
references: Science. 2008 Feb 8;319(5864):810-3
references: 18174397
references: Proc Natl Acad Sci U S A. 2000 Jan 4;97(1):343-8
references: 10618420
references: J Virol. 2004 Apr;78(7):3429-35
references: 15016865
references: J Virol. 2004 Jan;78(2):1026-31
references: 14694135
references: Biophys J. 1976 Sep;16(9):1055-69
references: 786399
references: Science. 2009 Mar 27;323(5922):1743-7
references: 19325119
references: Nat Rev Microbiol. 2008 Nov;6(11):815-26
references: 18923409
references: Science. 2007 Aug 24;317(5841):1072-6
references: 17717182
references: J Immunol. 1995 Jul 1;155(1):473-88
references: 7602119
references: J Cell Biol. 2012 Oct 29;199(3):467-79
references: 23091068
references: Nat Cell Biol. 2011 Apr;13(4):394-401
references: 21394083
references: J Virol. 1996 Oct;70(10):6547-56
references: 8794289
references: J Virol. 2006 Sep;80(17):8796-806
references: 16912326
references: J Virol. 2007 Sep;81(18):9999-10008
references: 17609279
references: J Virol. 2005 Oct;79(19):12231-41
references: 16160149
references: J Virol. 2011 Oct;85(19):9749-66
references: 21813604
references: J Immunol. 1997 Apr 15;158(8):3996-4007
references: 9103471
references: PLoS Pathog. 2011 Dec;7(12):e1002456
references: 22194693
references: Science. 2012 Oct 26;338(6106):524-8
references: 23112332
references: Nat Immunol. 2010 Jan;11(1):90-6
references: 20010844
references: J Virol. 1995 Jun;69(6):3824-30
references: 7745730
references: J Biol Chem. 2012 Aug 3;287(32):27158-67
references: 22700970
references: Biophys J. 2009 Aug 19;97(4):1095-103
references: 19686657
references: Nat Methods. 2008 Feb;5(2):155-7
references: 18193054
references: Nature. 2008 Jul 10;454(7201):236-40
references: 18500329
references: Nat Immunol. 2013 Jan;14(1):82-9
references: 23202272
references: Histochem Cell Biol. 2013 Jan;139(1):173-9
references: 22910843
references: J Virol. 1995 Mar;69(3):1984-9
references: 7853546
references: Virology. 1997 Nov 24;238(2):305-15
references: 9400603
references: Mol Biol Cell. 2007 Feb;18(2):414-25
references: 17108326
references: PLoS Pathog. 2013 Feb;9(2):e1003198
references: 23468635
references: Nat Cell Biol. 2011 Apr;13(4):469-74
references: 21394086
references: Biophys J. 2012 Apr 4;102(7):1534-42
references: 22500753
references: J Biophotonics. 2010 Jul;3(7):446-54
references: 20148419
references: J Virol. 1993 Apr;67(4):2182-90
references: 8445728
references: Biol Cell. 2010 Mar 25;102(6):335-50
references: 20356318
references: PLoS Pathog. 2009 Nov;5(11):e1000652
references: 19893629
references: Cold Spring Harb Perspect Med. 2012 Jul;2(7):a006924
references: 22762019
references: J Cell Sci. 1998 Jan;111 ( Pt 1):99-109
references: 9394016
references: J Virol. 1992 Aug;66(8):4966-71
references: 1629961
references: J Virol. 2007 Nov;81(22):12582-95
references: 17728240
references: Science. 2010 Jan 1;327(5961):46-50
references: 20044567
references: Proc Natl Acad Sci U S A. 2007 Oct 30;104(44):17370-5
references: 17959773
references: Virology. 2010 Sep 30;405(2):548-55
references: 20655565
references: Virology. 2009 May 10;387(2):341-52
references: 19285328
references: Nano Lett. 2012 Sep 12;12(9):4705-10
references: 22906128
references: J Virol. 2010 Jul;84(13):6352-66
references: 20392841
references: Science. 2006 Sep 15;313(5793):1642-5
references: 16902090
references: Traffic. 2010 Nov;11(11):1401-14
references: 20727121
references: Virology. 1992 Feb;186(2):712-24
references: 1370739
references: Biophys J. 2007 Mar 1;92(5):1777-83
references: 17158573
references: Nature. 2006 Jun 15;441(7095):847-52
references: 16728975
references: J Virol. 1993 Nov;67(11):6447-52
references: 8411347
references: J Cell Biol. 2011 Dec 26;195(7):1071-82
references: 22123832
references: Nature. 2012 Oct 11;490(7419):283-7
references: 22854780
references: J Virol. 2007 Jan;81(2):1000-12
references: 17079292
references: J Biol Chem. 1998 Jun 19;273(25):15773-8
references: 9624176
references: J Virol. 1994 Aug;68(8):5311-20
references: 8035531
references: Curr Protoc Cell Biol. 2003 Aug;Chapter 21:Unit 21.1
references: 18228432
references: Neuroscience. 2007 Jan 5;144(1):135-43
references: 17049171
references: J Virol. 2000 May;74(10):4891-3
references: 10775630
references: Nature. 2009 Feb 26;457(7233):1159-62
references: 19098897