How Polyomaviruses Exploit the ERAD Machinery to Cause Infection

Dupzyk, Allison; Tsai, Billy

doi:10.3390/v8090242

Cited by 34 publications

(32 citation statements)

References 102 publications

(142 reference statements)

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“…Trafficking of the particles from late endosomal compartments to ER and from ER to the cell nucleus is still not well understood. Evidence for the importance of residential ER chaperones and enzymes in viral infectivity strongly supports the hypothesis that polyomaviruses penetrate the membrane at the ER [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 56%

Hydrophobic domains of mouse polyomavirus minor capsid proteins promote membrane association and virus exit from the ER

et al. 2017

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The minor structural protein VP2 and its shorter variant, VP3, of mouse polyomavirus (MPyV) are essential for virus exit from the endoplasmic reticulum (ER) during viral trafficking to the nucleus. Here, we followed the role of putative hydrophobic domains (HD) of the minor proteins in membrane affinity and viral infectivity. We prepared variants of VP2, each mutated to decrease hydrophobicity of one of three predicted hydrophobic domains: VP2-mHD1, VP2-mHD2 or VP2-mHD3 mutated in HD1 (amino acids (aa) 60-101), HD2 (aa 125-165) or HD3 (aa 287-307), respectively. Transient production of the mutated proteins revealed that only VP2-mHD2 lost the affinity for intracellular membranes. Cytotoxicity connected with the ability of VP2/VP3 to perforate membranes decreased markedly for VP2-mHD2, but only slightly for VP2-mHD1. The mutant VP2-mHD3 exhibited properties similar to the wild-type protein. MPyV genomes, each carrying one of the mutations, were prepared for virus production. MPyV-mHD1 and MPyVmHD2 viruses could be isolated, while the HD3 mutation in VP2/VP3 prevented virus assembly. We found that both MPyV-mHD1 and MPyV-mHD2 viruses arrived at the ER without delay and were processed by ER residential enzymes. However, the ability to associate with ER membranes was decreased in the case of MPyV-mHD1 and practically abolished in the case of MPyV-mHD2. Interestingly, while MPyV-mHD2 was not infectious, infection of MPyV-mHD1 virus was delayed. These findings reveal that HD2, common to both VP2 and VP3, is responsible for the membrane binding properties of the minor proteins, while HD1 of VP2 is likely required to stabilize VP2-membrane association and to enhance viral exit from the ER.

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Section: Introductionmentioning

confidence: 56%

Hydrophobic domains of mouse polyomavirus minor capsid proteins promote membrane association and virus exit from the ER

et al. 2017

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“…1 C) and may therefore be dependent on the redox environment within the ER. In analogy to SV40, uncoating and membrane translocation to the cytoplasm may occur in the ER with the help of the ERAD machinery and cytoplasmic chaperones (39, 40).…”

Section: Discussionmentioning

confidence: 99%

“…Host cell entry of most PyV occurs by caveolar/lipid raft-mediated endocytosis (34-37), whereas JC virus, for example, uses CME (38). After endocytosis, virions are routed through the endosomal pathway to be delivered to the ER (39). There, a chaperone- and disulfide isomerase-mediated uncoating step occurs, whereupon the modified particles are translocated into the cytosol by the ER-associated degradation machinery (40-43).…”

Section: Introductionmentioning

confidence: 99%

Infectious Entry of Merkel Cell Polyomavirus

Becker

Dominguez

Greune

et al. 2018

Preprint

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27Merkel Cell Polyomavirus (MCPyV) is a small, non-enveloped tumor virus associated 28 with an aggressive form of skin cancer, the Merkel cell carcinoma (MCC). MCPyV 29 infections are highly prevalent in the human population with MCPyV virions being 30 continuously shed from human skin. However, the precise host cell tropism(s) of 31MCPyV remains unclear: MCPyV is able to replicate within a subset of dermal 32fibroblasts, but MCPyV DNA has also been detected in a variety of other tissues. 33However, MCPyV appears different from other polyomaviruses as it requires sulfated 34 polysaccharides such as heparan sulfates and/or chondroitin sulfates for initial 35 attachment. Like other polyomaviruses, MCPyV engages sialic acid as a (co-36 )receptor. To explore the infectious entry process of MCPyV, we analyzed the cell 37 biological determinants of MCPyV entry into A549 cells, a highly transducible lung 38 carcinoma cell line, in comparison to well-studied simian virus 40 and a number of 39 other viruses. Our results indicate that MCPyV enters cells via caveolar/lipid raft-40 mediated endocytosis but not macropinocytosis, clathrin-mediated endocytosis or 41 glycosphingolipid-enriched carriers. The viruses internalized in small endocytic pits 42 that led the virus to endosomes and from there to the endoplasmic reticulum (ER). 43Similar to other polyomaviruses, trafficking required microtubular transport, 44 acidification of endosomes, and a functional redox environment. To our surprise, the 45 virus was found to acquire a membrane envelope within endosomes, a phenomenon 46 not reported for other viruses. Only minor amounts of viruses reached the ER, while 47 the majority was retained in endosomal compartments suggesting that endosome-to-48 ER trafficking is a bottleneck during infectious entry. 49 50 51 52 3 Importance 53 MCPyV is the first polyomavirus directly implicated in the development of an 54 aggressive human cancer, the Merkel Cell Carcinoma (MCC). Although MCPyV is 55 constantly shed from healthy skin, MCC incidence increases among aging and 56 immunocompromised individuals. To date, the events connecting initial MCPyV 57 infection and subsequent transformation still remain elusive. MCPyV differs from 58 other known polyomaviruses concerning its cell tropism, entry receptor requirements, 59 and infection kinetics. In this study, we examined the cellular requirements for 60 endocytic entry as well as the subcellular localization of incoming virus particles. A 61 thorough understanding of the determinants of the infectious entry pathway and the 62 specific biological niche will benefit prevention of virus-derived cancers such as 63 MCC. 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 Polyomaviruses (PyV) are small, non-enveloped dsDNA viruses with a diameter of 80 45-50 nm. The icosahedral (T=7) capids consist of 72 homopentameric capsomers of 81 the major capid protein VP1 with minor capsid proteins VP2/VP3 located within a 82 cavity underneath the VP1 pentamers. The PyV capsid harbors a chromatinized, 83 circu...

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“…Next, we examined whether D1min treatment affects the ER-to-cytosol retrotranslocation of BKV, 376 a critical entry step and distinguishing feature of polyomaviruses (Dupzyk and Tsai, 2016). This 377 transition can be assayed by fractionation of infected host cells and testing for the presence of 378 VP1 protein in the cytosolic fraction (Bennett et al, 2013;Inoue and Tsai, 2011).…”

Section: D1min Activity Occurs Prior To Bkv Er-to-cytosol Retrotranslmentioning

confidence: 99%

A VP2/3-derived peptide exhibits potent antiviral activity against BK and JC polyomaviruses by targeting a novel VP1 binding site

Kane

Fong

Shaul

et al. 2019

Preprint

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28In pursuit of effective therapeutics for human polyomaviruses, we identified a peptide derived from 29 the BK polyomavirus (BKV) minor structural proteins VP2/3 that is a potent inhibitor of BKV 30 infection with no observable cellular toxicity. The thirteen amino acid peptide binds to major 31 structural protein VP1 in a new location within the pore with a low nanomolar KD. Alanine scanning 32 of the peptide identified three key residues, substitution of each of which results in ~1000-fold 33 loss of affinity with a concomitant reduction in antiviral activity. NMR spectroscopy and an X-ray 34 structurally-guided model demonstrate specific binding of the peptide to the pore of the VP1 35 pentamer that constitutes the BKV capsid. Cell-based assays with the peptide demonstrate 36 nanomolar inhibition of BKV infection and suggest that the peptide likely blocks the viral entry 37 pathway between endocytosis and escape from the host cell ER. The peptide motif is highly 38 conserved among the polyomavirus clade, and homologous peptides exhibit similar binding 39 properties for JC polyomavirus and inhibit infection with similar potency to BKV in a model cell 40 line. Substitutions within VP1 or VP2/3 residues involved in VP1-peptide interaction negatively 41 impact viral infectivity, potentially indicating the peptide-binding site within the VP1 pore is relevant 42 for VP1-VP2/3 interactions. The inhibitory potential of the peptide-binding site first reported here 43 may present a novel target for development of new anti-polyomavirus therapies. In summary, we 44 present the first anti-polyomavirus inhibitor that acts via a novel mechanism of action by 45 specifically targeting the pore of VP1. 46 47 48 53 54

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How Polyomaviruses Exploit the ERAD Machinery to Cause Infection

Cited by 34 publications

References 102 publications

Hydrophobic domains of mouse polyomavirus minor capsid proteins promote membrane association and virus exit from the ER

Hydrophobic domains of mouse polyomavirus minor capsid proteins promote membrane association and virus exit from the ER

Infectious Entry of Merkel Cell Polyomavirus

A VP2/3-derived peptide exhibits potent antiviral activity against BK and JC polyomaviruses by targeting a novel VP1 binding site

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