A Tyrosine Motif in the Cytoplasmic Domain of Mason-Pfizer Monkey Virus Is Essential for the Incorporation of Glycoprotein into Virions

Cao, Song; Dubay, Susan R.; Hunter, Eric

doi:10.1128/jvi.77.9.5192-5200.2003

Cited by 25 publications

(44 citation statements)

References 55 publications

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“…The TM glycoprotein also mediates virus-cell membrane fusion during viral entry as well as cell-cell fusion via a fusion peptide and heptad repeat motifs located at the extracellular domain (2,18,35,69,74,76). This fusion process also is influenced by the cytoplasmic domain of the TM glycoprotein as demonstrated previously (9,13,19,36,44,55,68,70).As is observed with murine leukemia virus (MuLV) and Gibbon ape leukemia virus, but unlike most other retroviruses, a viral protease-mediated maturational cleavage of the TM cytoplasmic domain occurs following virus release, which results in conversion of gp22 into gp20 (9,10,13,55,67). Based on cytoplasmic domain truncation mutants, this maturational cleavage of the cytoplasmic domain appears to dramatically increase the fusion activity of the TM proteins and results in the loss of 17 amino acids from the carboxy terminus of the cytoplasmic domain (9, 68).…”

mentioning

confidence: 69%

“…For retroviruses, which do not require glycoprotein expression for virus assembly and release, the nature of capsidenvelope interactions is less well defined. In M-PMV, the glycoprotein appears to play an important role in intracellular transport of assembled capsids to the plasma membrane, and mutations that interfere with Env incorporation also decrease the efficiency of virus release (64,65,68). In contrast, Rous sarcoma virus, which encodes a glycoprotein lacking a cytoplasmic domain, can efficiently assemble and infect cells (53).…”

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confidence: 99%

“…It is then cleaved by a cellular protease into two subunits, gp70 (SU) and gp22 (TM), in a late compartment of the Golgi complex (26). The oligomeric, noncovalently associated gp70 and gp22 complexes are then transported to the plasma membrane, where they are incorporated into budding virions (10,68). The SU glycoprotein is responsible for receptor binding, whereas the TM glycoprotein is responsible for anchoring the SU protein at the surface of infected cells or the viral membrane.…”

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confidence: 99%

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Amino Acid Residues in the Cytoplasmic Domain of the Mason-Pfizer Monkey Virus Glycoprotein Critical for Its Incorporation into Virions

Cao

Micoli

Bauerová

et al. 2005

J Virol

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The envelope (Env) glycoprotein of Mason-Pfizer monkey virus (M-PMV), like those of other retroviruses, is synthesized on the rough endoplasmic reticulum (ER) and is cotranslationally glycosylated and inserted into the lumen of the ER (5-8, 30). Shortly after synthesis, the glycosylated precursor is assembled into trimers, a process which is thought to be required for transport of Env from the ER to the Golgi complex (2,20). It is then cleaved by a cellular protease into two subunits, gp70 (SU) and gp22 (TM), in a late compartment of the Golgi complex (26). The oligomeric, noncovalently associated gp70 and gp22 complexes are then transported to the plasma membrane, where they are incorporated into budding virions (10, 68). The SU glycoprotein is responsible for receptor binding, whereas the TM glycoprotein is responsible for anchoring the SU protein at the surface of infected cells or the viral membrane. The TM glycoprotein also mediates virus-cell membrane fusion during viral entry as well as cell-cell fusion via a fusion peptide and heptad repeat motifs located at the extracellular domain (2,18,35,69,74,76). This fusion process also is influenced by the cytoplasmic domain of the TM glycoprotein as demonstrated previously (9,13,19,36,44,55,68,70).As is observed with murine leukemia virus (MuLV) and Gibbon ape leukemia virus, but unlike most other retroviruses, a viral protease-mediated maturational cleavage of the TM cytoplasmic domain occurs following virus release, which results in conversion of gp22 into gp20 (9,10,13,55,67). Based on cytoplasmic domain truncation mutants, this maturational cleavage of the cytoplasmic domain appears to dramatically increase the fusion activity of the TM proteins and results in the loss of 17 amino acids from the carboxy terminus of the cytoplasmic domain (9, 68).The incorporation of glycoprotein into budding virions is essential for the formation of an infectious virus particle, since retrovirus Env proteins play important roles in receptor binding and membrane fusion. In the case of the alphaviruses, an interaction between the cytoplasmic domain of the spike glycoprotein and the virus nucleocapsid has been demonstrated directly and is absolutely required for virus budding (1,23,72,87). For retroviruses, which do not require glycoprotein expression for virus assembly and release, the nature of capsidenvelope interactions is less well defined. In M-PMV, the glycoprotein appears to play an important role in intracellular transport of assembled capsids to the plasma membrane, and mutations that interfere with Env incorporation also decrease the efficiency of virus release (64,65,68). In contrast, Rous sarcoma virus, which encodes a glycoprotein lacking a cytoplasmic domain, can efficiently assemble and infect cells (53). In the case of Moloney MuLV, some deletion mutations in the cytoplasmic domain of the TM protein decrease infectivity without reducing glycoprotein incorporation (33). Evidence derived from Env and Gag mutagenesis and pseudotyping

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confidence: 69%

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confidence: 99%

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confidence: 99%

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Amino Acid Residues in the Cytoplasmic Domain of the Mason-Pfizer Monkey Virus Glycoprotein Critical for Its Incorporation into Virions

Cao

Micoli

Bauerová

et al. 2005

J Virol

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“…Thus, such dual control strongly suppresses cellcell fusion, as demonstrated by cytoplasmic-tail mutants (1,11,25,26,46,51,70) and by the discovery of highly cell-cellfusogenic endogenous retroviral glycoproteins that lack such determinants (6, 7). Several motifs in the cytoplasmic tails of retroviral Env glycoproteins have been shown to regulate their intracellular trafficking via their interactions with intracellular effectors (1,5,16,22,28,57). A tyrosine motif is implicated in the basolateral sorting of Env in polarized cells (28) and in the endocytosis of Env from the plasma membrane via the recruitment of the cellular clathrin-adaptor complex AP-2 (5, 9, 39).…”

Section: Discussionmentioning

confidence: 99%

Intracellular Trafficking of Gag and Env Proteins and Their Interactions Modulate Pseudotyping of Retroviruses

Sandrin

Muriaux

Darlix

et al. 2004

J Virol

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Glycoproteins derived from most retroviruses and from several families of enveloped viruses can form infectious pseudotypes with murine leukemia virus (MLV) and lentiviral core particles, like the MLV envelope glycoproteins (Env) that are incorporated on either virus type. However, coexpression of a given glycoprotein with heterologous core proteins does not always give rise to highly infectious viral particles, and restrictions on pseudotype formation have been reported. To understand the mechanisms that control the recruitment of viral surface glycoproteins on lentiviral and retroviral cores, we exploited the fact that the feline endogenous retrovirus RD114 glycoprotein does not efficiently pseudotype lentiviral cores derived from simian immunodeficiency virus, whereas it is readily incorporated onto MLV particles. Our results indicate that recruitment of glycoproteins by the MLV and lentiviral core proteins occurs in intracellular compartments and not at the cell surface. We found that Env and core protein colocalization in intracytoplasmic vesicles is required for pseudotype formation. By investigating MLV/RD114 Env chimeras, we show that signals in the cytoplasmic tail of either glycoprotein differentially influenced their intracellular localization; that of MLV allows endosomal localization and hence recruitment by both lentiviral and MLV cores. Furthermore, we found that upon membrane binding, MLV core proteins could relocalize Env glycoproteins in late endosomes and allow their incorporation on viral particles. Thus, intracellular colocalization, as well as interactions between Env and core proteins, may influence the recruitment of the glycoprotein onto viral particles and generate infectious pseudotyped viruses.Enveloped viruses consist of nucleocapsids that are surrounded by a host-derived membrane envelope onto which are placed the viral surface glycoproteins. While the nucleocapsid contains the determinants that specify replication of the viral genome, the primary role of the envelope glycoproteins is to allow the entry of the virion into new cells through binding to cell surface receptors and subsequent triggering of fusion between the viral and cell membranes. The two types of viral structural determinants are expressed in distinct locations, in the cytosol for the nucleocapsid proteins and in the secretory pathway for the envelope glycoproteins (59). For retroviruses, it is not clear how the Gag and Env proteins, which form their nucleocapsid and envelope proteins, respectively, as well as the viral genomic RNAs, reach common sites to assemble, bud, and form infectious virions. In particular, the mechanisms that allow the recruitment of the viral glycoproteins onto retroviral cores are poorly understood.So far, we know of at least two mechanisms that lead to the incorporation of viral or cellular glycoproteins onto viral particles. In the active model of Env glycoprotein incorporation (59), the assembly of viral particles depends either on direct interaction between the cytoplasmic tail of the ps...

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“…The involvement of CTDs of viral envelope proteins in the budding process has indeed been supported for a number of other viruses, including Sendai virus (Ali & Nayak, 2000), influenza A virus (Bilsel et al, 1993), VSV (Robison & Whitt, 2000), Mason-Pfizer monkey virus (Song et al, 2003) and Semliki Forest virus (Zhao et al, 1994). It is plausible that there is an interaction between the CTD of F and one or more viral NC proteins that are specific for group II NPVs.…”

Section: Discussionmentioning

confidence: 99%

GP64 of group I nucleopolyhedroviruses cannot readily rescue infectivity of group II f-null nucleopolyhedroviruses

Westenberg

Vlak

2008

Journal of General Virology

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The genus Nucleopolyhedrovirus (NPV) of the family Baculoviridae can be subdivided phylogenetically into two groups. The same division can be made on the basis of their budded virus (BV) envelope fusion protein. Group I NPVs are characterized by the presence of a GP64-like major envelope fusion protein, which is involved in viral attachment and the fusion of virus and cell membrane, and is required for budding of progeny nucleocapsids. Group II NPVs have an envelope fusion protein unrelated to GP64, named F. In contrast to GP64, F proteins are found in all baculoviruses, but they are not functional as envelope fusion proteins in group I NPVs. Autographa californica multiple NPV (AcMNPV) lacking GP64 can be pseudotyped by the F protein of Spodoptera exigua multiple NPV (SeMNPV), suggesting that F proteins are functionally analogous to GP64. GP64 homologues are thought to have been acquired by group I NPVs during evolution, thereby giving these viruses a selective advantage and obviating the need for a functional F protein. To address this supposition experimentally, attempts were made to pseudotype a group II NPV, SeMNPV, with GP64. Transfection of an f-null SeMNPV bacmid into Se301 cells did not result in the production of infectious BVs. This defect was rescued by insertion of SeMNPV f, but not by insertion of AcMNPV gp64. This suggests that the functional analogy between GP64 and F is not readily reciprocal and that F proteins from group II NPVs may provide additional functions in BV formation that are lacking in the GP64 type of fusion protein.

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A Tyrosine Motif in the Cytoplasmic Domain of Mason-Pfizer Monkey Virus Is Essential for the Incorporation of Glycoprotein into Virions

Cited by 25 publications

References 55 publications

Amino Acid Residues in the Cytoplasmic Domain of the Mason-Pfizer Monkey Virus Glycoprotein Critical for Its Incorporation into Virions

Amino Acid Residues in the Cytoplasmic Domain of the Mason-Pfizer Monkey Virus Glycoprotein Critical for Its Incorporation into Virions

Intracellular Trafficking of Gag and Env Proteins and Their Interactions Modulate Pseudotyping of Retroviruses

GP64 of group I nucleopolyhedroviruses cannot readily rescue infectivity of group II f-null nucleopolyhedroviruses

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