PMID:2200886

Citation	Lobigs, M, Zhao, HX and Garoff, H (1990) Function of Semliki Forest virus E3 peptide in virus assembly: replacement of E3 with an artificial signal peptide abolishes spike heterodimerization and surface expression of E1. J. Virol. 64:4346-55
Abstract	The Semliki Forest virus spike glycoproteins E1 and p62 form a heterodimeric complex in the endoplasmic reticulum (ER) and are transported as such to the cell surface. In the mature virus particle, the heterodimeric association of E1 and E2 (the cleavage product of p62) is maintained, but as a more labile and acid-sensitive oligomer than the E1-p62 complex. The E3 peptide forms the N-terminal part of the p62 precursor and carries the signal for the translocation of p62 into the lumen of the ER. The question of whether E3 is also important in the formation and stabilization of the E1-p62 heterodimer has been addressed here with the aid of an E3 deletion mutant cDNA. In this construct, the entire E3 was replaced with a cleavable, artificial signal sequence which preserved the membrane topology of an authentic E2. The E3 deletion, when expressed via a recombinant vaccinia virus, abolished heterodimerization of the spike proteins. It also resulted in the complete retention of E1 in the ER and almost total inhibition of E2 transport to the plasma membrane. The oligomerization and transport defect of E1 expressed from the E3 deletion mutant could be complemented with a wild-type p62 provided from a separate coding unit in double infections. These results point to a central role of E3 in complex formation and transport of the viral structural components to the site of budding. In conjunction with earlier work (M. Lobigs and H. Garoff, J. Virol. 64:1233-1240, 1990; J. Wahlberg, W. A. M. Boere, and H. Garoff, J. Virol. 63:4991-4997, 1989), the data support a model of spike protein oligomerization control of Semliki Forest virus assembly and disassembly which may be mediated by the presence of E3 in the uncleaved p62 precursor and release of E3 after cleavage.
Links	PubMed PMC247902
Keywords	Animals; Base Sequence; Cell Line; Cell Membrane/metabolism; Cell Membrane/ultrastructure; Fluorescent Antibody Technique; Genetic Complementation Test; Kinetics; Macromolecular Substances; Molecular Sequence Data; Mutation; Oligonucleotide Probes; Semliki forest virus/genetics; Semliki forest virus/physiology; Time Factors; Transfection; Viral Proteins/analysis; Viral Proteins/biosynthesis; Viral Proteins/genetics
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
SINDV:POLS	Contributes to	GO:0039619: T=4 icosahedral viral capsid	ECO:0000315:		C		in figure 2.(lane 8,9,11,12)). "This suggests that in the absence of E3, the spike glycoproteins do not form heterodimeric complexes at any time after synthesis"(involved in virus assembly). Lobigs,M. et at.(1990).	complete CACAO 9562
SFV:POLS	involved_in	GO:0019068: virion assembly	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
SFV:POLS		GO:0019068: virion assembly	ECO:0000315:		P		in figure 2.(lane 8,9,11,12)). "This suggests that in the absence of E3, the spike glycoproteins do not form heterodimeric complexes at any time after synthesis"(involved in virus assembly). Lobigs,M. et at.(1990).	complete CACAO 9942
EEVVT:POLS	NOT	GO:0039619: T=4 icosahedral viral capsid	ECO:0000315:		C		in figure 2.(lane 8,9,11,12)). "This suggests that in the absence of E3, the spike glycoproteins do not form heterodimeric complexes at any time after synthesis"(involved in virus assembly). Lobigs,M. et at.(1990).	complete CACAO 9943
EEVV3:POLS	NOT	GO:0039619: T=4 icosahedral viral capsid	ECO:0000315:		C		in figure 2.(lane 8,9,11,12)). "This suggests that in the absence of E3, the spike glycoproteins do not form heterodimeric complexes at any time after synthesis"(involved in virus assembly). Lobigs,M. et at.(1990).	complete CACAO 9948

References

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