The open reading frame VI product of Cauliflower mosaic virus is a nucleocytoplasmic protein: its N terminus mediates its nuclear export and formation of electron-dense viroplasms.
The Cauliflower mosaic virus (CaMV) open reading frame VI product (P6) is essential for the viral infection cycle. It controls translation reinitiation of the viral polycistronic RNAs and forms cytoplasmic inclusion bodies (viroplasms) where virus replication and assembly occur. In this study, the mechanism involved in viroplasm formation was investigated by in vitro and in vivo experiments. Far protein gel blot assays using a collection of P6 deletion mutants demonstrated that the N-terminal alpha-helix of P6 mediates interaction between P6 molecules. Transient expression in tobacco (Nicotiana tabacum) BY-2 cells of full-length P6 and P6 mutants fused to enhanced green fluorescent protein revealed that viroplasms are formed at the periphery of the nucleus and that the N-terminal domain of P6 is an important determinant in this process. Finally, this study led to the unexpected finding that P6 is a nucleocytoplasmic shuttle protein and that its nuclear export is mediated by a Leu-rich sequence that is part of the alpha-helix domain implicated in viroplasm formation. The discovery that P6 can localize to the nucleus opens new prospects for understanding yet unknown roles of this viral protein in the course of the CaMV infection cycle.
Haas
Muriel
M
Institut de Biologie Moléculaire des Plantes, Unité Propre de Recherche, Centre National de la Recherche Scientifique 2357, Université Louis Pasteur, 67084 Strasbourg Cedex, France.
Geldreich
Angèle
A
Bureau
Marina
M
Dupuis
Laurence
L
Leh
Véronique
V
Vetter
Guillaume
G
Kobayashi
Kappei
K
Hohn
Thomas
T
Ryabova
Lyubov
L
Yot
Pierre
P
Keller
Mario
M
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D001483:Base Sequence; D029741:Brassica rapa / Q000821:virology; D017796:Caulimovirus / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D004279:DNA, Viral / Q000235:genetics; D005814:Genes, Viral; D007181:Inclusion Bodies, Viral / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation; D029543:Nucleocytoplasmic Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016366:Open Reading Frames; D010935:Plant Diseases / Q000821:virology; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000821:virology; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D004279:DNA, Viral; D029543:Nucleocytoplasmic Transport Proteins; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014764:Viral Proteins; C095687:gene VI protein, Cauliflower mosaic virus; C065790:viroplasmin protein, Cauliflower mosaic virus
J Comput Biol. 1995 Spring;2(1):125-38
7497115
Mol Plant Microbe Interact. 2000 Nov;13(11):1275-9
11059496
Annu Rev Microbiol. 1998;52:491-532
9891806
Prog Nucleic Acid Res Mol Biol. 2002;72:1-39
12206450
Plant Physiol. 1995 Apr;107(4):1201-8
7770524
Mol Plant Pathol. 2002 Nov 1;3(6):419-29
20569349
J Gen Virol. 1999 Feb;80 ( Pt 2):333-9
10073692
J Cell Biol. 2001 Apr 30;153(3):449-55
11331297
Virology. 1991 Nov;185(1):337-44
1656590
J Cell Biol. 1998 Dec 28;143(7):1883-98
9864362
Annu Rev Cell Dev Biol. 1999;15:607-60
10611974
Virus Genes. 1996;13(1):5-17
8938975
Mol Plant Microbe Interact. 2001 Jan;14(1):31-41
11194869
Mol Plant Microbe Interact. 1990 Sep-Oct;3(5):341-5
2134858
Virology. 1980 Apr 30;102(2):381-8
18631647
Plasmid. 1983 Jan;9(1):31-41
6300943
J Mol Appl Genet. 1984;2(6):537-47
6530602
Curr Biol. 2002 Jan 8;12(1):1-11
11790298
Virology. 1989 Apr;169(2):436-46
2705305
Mol Plant Microbe Interact. 1998 Jul;11(7):618-25
9650295
Cell. 2001 Jan 26;104(2):173-6
11207359
J Virol. 2003 Aug;77(15):8577-83
12857928
Trends Cell Biol. 2000 Dec;10(12):524-30
11121744
Curr Opin Struct Biol. 1997 Jun;7(3):388-93
9204281
Mol Cell Biol. 1986 Jul;6(7):2632-7
3785205
Virology. 1998 Mar 15;242(2):395-402
9514961
Virology. 2000 Jan 5;266(1):1-7
10612654
J Cell Biol. 1975 Dec;67(3):835-51
811671
Curr Opin Cell Biol. 2002 Jun;14(3):328-35
12067655
EMBO J. 1995 Jul 17;14(14):3552-62
7628455
EMBO J. 1993 Aug;12(8):3305-14
8344266
Virology. 1996 Mar 1;217(1):147-57
8599199
J Gen Virol. 2004 Dec;85(Pt 12):3765-75
15557250
Mol Plant Microbe Interact. 1997 Dec;10(9):1094-101
9390424
J Cell Sci. 1994 Feb;107 ( Pt 2):385-99
8207070
Nucleic Acids Res. 1998 Apr 1;26(7):1834-40
9512560
Cell. 2001 Sep 21;106(6):723-33
11572778
Phytopathology. 2002 Feb;92(2):190-6
18943093
Adv Virus Res. 1994;44:1-67
7817872
Mol Plant Microbe Interact. 2002 Oct;15(10):1050-7
12437303
Plant Cell. 1999 Jul;11(7):1267-76
10402428
Proc Natl Acad Sci U S A. 2002 Feb 19;99(4):2422-7
11842201
Microbiol Immunol. 1998;42(1):65-9
9525783
Mol Plant Microbe Interact. 1999 May;12(5):377-84
10226370
EMBO J. 2002 Feb 1;21(3):377-86
11823430
Nat Rev Mol Cell Biol. 2003 Aug;4(8):605-12
12923522
Cell. 1997 Sep 19;90(6):1051-60
9323133
Exp Cell Res. 1998 Aug 1;242(2):540-7
9683540