Role of a nuclear localization signal on the minor capsid Proteins VP2 and VP3 in BKPyV nuclear entry

Bennett, Shauna M.; Zhao, Linbo; Bosard, Catherine; Imperiale, Michael J.

doi:10.1016/j.virol.2014.10.013

Cited by 57 publications

(64 citation statements)

References 29 publications

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“…To investigate this, one could make other VP3-deficient mutants by replacing this methionine in VP2 with less bulky amino acids. Although the entry of BKPyV and SV40 into host cells is not fully understood, SV40 VP2 in particular seems to play essential roles in the transport of the partly dissembled particles from the endoplasmic reticulum (ER) to the cytosol (47-49), while both VP2 and VP3 for both SV40 and BKPyV are important for the nuclear import of the viral genomes (50,51). So far, we do not know which of these steps are disrupted during infection with our mutants.…”

Section: Discussionmentioning

confidence: 95%

The Presumed Polyomavirus Viroporin VP4 of Simian Virus 40 or Human BK Polyomavirus Is Not Required for Viral Progeny Release

Henriksen

Hansen

Bruun

et al. 2016

J Virol

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The minor capsid protein of human BK polyomavirus (BKPyV), VP2, and its N-terminally truncated form, VP3, are both important for viral entry. The closely related simian virus 40 (SV40) reportedly produces an additional truncated form of VP2/3, denoted VP4, apparently functioning as a viroporin promoting progeny release. The VP4 open reading frame is conserved in some polyomaviruses, including BKPyV. In this study, we investigated the role of VP4 in BKPyV replication. By transfecting viral genomes into primary human renal proximal tubule epithelial cells, we demonstrated that unaltered BKPyV and mutants with start codon substitutions in VP4 (VP2M229I and VP2M229A) abolishing putative VP4 production were released at the same level to supernatants. However, during infection studies, VP2M229I and VP2M229A exhibited 90% and 65% reduced infectivity, respectively, indicating that isoleucine substitution inadvertently disrupted VP2/3 function to the detriment of viral entry, while inhibition of VP4 production during late infection was well tolerated. Unexpectedly, and similarly to BKPyV, wild-type SV40 and the corresponding VP4 start codon mutants (VP2M228I and VP2M228A) transfected into monkey kidney cell lines were also released at equal levels. Upon infection, only the VP2M228I mutant exhibited reduced infectivity, a 43% reduction, which also subsequently led to delayed host cell lysis. Mass spectrometry analysis of nuclear extracts from SV40-infected cells failed to identify VP4. Our results suggest that neither BKPyV nor SV40 require VP4 for progeny release. Moreover, our results reveal an important role in viral entry for the amino acid in VP2/VP3 unavoidably changed by VP4 start codon mutagenesis. IMPORTANCEAlmost a decade ago, SV40 was reported to produce a late nonstructural protein, VP4, which forms pores in the nuclear membrane, facilitating progeny release. By performing transfection studies with unaltered BKPyV and SV40 and their respective VP4-deficient mutants, we found that VP4 is dispensable for progeny release, contrary to the original findings. However, infection studies demonstrated a counterintuitive reduction of infectivity of certain VP4-deficient mutants. In addition to the isoleucine-substituted SV40 mutant of the original study, we included alanine-substituted VP4-deficient mutants of BKPyV (VP2M229A) and SV40 (VP2M228A). These revealed that the reduction in infectivity was not caused by a lack of VP4 but rather depended on the identity of the single amino acid substituted within VP2/3 for VP4 start codon mutagenesis. Hopefully, our results will correct the longstanding misconception of VP4's role during infection and stimulate continued work on unraveling the mechanism for release of polyomavirus progeny. Currently there are 13 known species of human polyomaviruses, and of these at least four are associated with diseases mainly affecting immunocompromised patients. BK polyomavirus (BKPyV) is the chief agent of polyomavirus-associated nephropathy (PyVAN) and polyomavirus-associated hemo...

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Section: Discussionmentioning

confidence: 95%

The Presumed Polyomavirus Viroporin VP4 of Simian Virus 40 or Human BK Polyomavirus Is Not Required for Viral Progeny Release

Henriksen

Hansen

Bruun

et al. 2016

J Virol

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“…Since BKPyV VP2 and VP3 share homology with that of SV40 at the basic C-terminal amino acids important for nuclear localization, elegant site-directed BKPyV VP2 and VP3 mutation and drug-based inhibition of IMP␤ in RPTE cells have been designed to ascertain the commonality of nuclear entry mechanism (Bennett et al 2015). This study could show that specific lysines in VP2 and VP3 are important for localization of BKPyV to the nucleus and that VP2K319T and VP3K200T mutants were defective in nuclear localization.…”

Section: Nuclear Entrymentioning

confidence: 99%

Entry, infection, replication, and egress of human polyomaviruses: an update

Bhattacharjee

Chattaraj

2017

Can. J. Microbiol.

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Polyomaviruses (PyVs), belonging to the family Polyomaviridae, are a group of small, nonenveloped, double-stranded, circular DNA viruses widely distributed in the vertebrates. PyVs cause no apparent disease in adult laboratory mice but cause a wide variety of tumors when artificially inoculated into neonates or semipermissive animals. A few human PyVs, such as BK, JC, and Merkel cell PyVs, have been unequivocally linked to pathogenesis under conditions of immunosuppression. Infection is thought to occur early in life and persists for the lifespan of the host. Over evolutionary time scales, it appears that PyVs have slowly co-evolved with specific host animal lineages. Host cell surface glycoproteins and glycolipids seem to play a decisive role in the entry stage of viral infection and in channeling the virions to specific intracellular membrane-bound compartments and ultimately to the nucleus, where the genomes are replicated and packaged for release. Therefore the transport of the infecting virion or viral genome to this site of multiplication is an essential process in productive viral infection as well as in latent infection and transformation. This review summarizes the major findings related to the characterization of the nature of the interactions between PyV and host protein and their impact in host cell invasion.

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“…After partial uncoating of the virus by reduction and isomerization of the disulfide bonds that link VP1 proteins, BK virus retrotranslocates to the cytosol for a second rearrangement of the capsid, thereby enabling a liaison to the nuclear pore and passage of viral DNA into the cell nucleus, 39 possibly facilitated by nuclear localization signals on the minor capsid proteins, VP2 and VP3. 40 After infection of human kidney epithelial cells in vitro, LT expression is observed at 36 hours before VP1 expression and viral DNA replication 41 and is required for viral DNA replication and expression of the late genes. 42 It can also induce an oncogenic effect by specifically binding and inactivating tumor suppressor proteins, including retinoblastoma family genes and p53 (Figure 1).…”

Section: Role Of the Viral Proteinsmentioning

confidence: 99%

BK Polyomavirus and the Transplanted Kidney

et al. 2016

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BK polyomavirus is ubiquitous, with a seropositivity rate of over 75% in the adult population. Primary infection is thought to occur in the respiratory tract, but asymptomatic BK virus latency is established in the urothelium. In immunocompromised host, the virus can reactivate but rarely compromises kidney function except in renal grafts, where it causes a tubulointerstitial inflammatory response similar to acute rejection. Restoring host immunity against the virus is the cornerstone of treatment. This review covers the virus-intrinsic features, the posttransplant microenvironment as well as the host immune factors that underlie the pathophysiology of polyomavirus-associated nephropathy. Current and promising therapeutic approaches to treat or prevent this complication are discussed in relation to the complex immunopathology of this condition.

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Role of a nuclear localization signal on the minor capsid Proteins VP2 and VP3 in BKPyV nuclear entry

Cited by 57 publications

References 29 publications

The Presumed Polyomavirus Viroporin VP4 of Simian Virus 40 or Human BK Polyomavirus Is Not Required for Viral Progeny Release

The Presumed Polyomavirus Viroporin VP4 of Simian Virus 40 or Human BK Polyomavirus Is Not Required for Viral Progeny Release

Entry, infection, replication, and egress of human polyomaviruses: an update

BK Polyomavirus and the Transplanted Kidney

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