Gene delivery via polyomavirus major capsid protein VP1, isolated from recombinant Escherichia coli

Viruses with spindle or lemon-shaped virions are rare in the world of viruses, but are common in viruses of archaeal extremophiles, possibly due to the extreme conditions in which they thrive. However, the structural and genetic basis for the unique spindle shape is unknown. The best-studied spindle-shaped virus, SSV1, is composed mostly of the major capsid protein VP1. Similar to many other viruses, proteolytic cleavage of VP1 is thought to be critical for virion formation. Unlike half of the genes in SSV1, including the minor capsid protein gene vp3, the vp1 gene does not tolerate deletion or transposon insertion. In order determine the role of the vp1 gene and its proteolysis for virus function, we developed techniques for site-directed mutagenesis of the SSV1 genome and complemented deletion mutants with vp1 genes from other SSVs. By analyzing these mutants we demonstrate that the N-terminus of the VP1 protein is required, but the N-terminus, or entire SSV1 VP1 protein, can be exchanged with VP1s from other SSVs. However, the conserved glutamate at the cleavage site is not essential for infectivity. Interestingly, viruses containing point mutations at this position generate mostly abnormal virions.

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Genetic Analysis of the Major Capsid Protein of the Archaeal Fusellovirus SSV1: Mutational Flexibility and Conformational Change

10.20944/preprints201711.0086.v1 ◽

2017 ◽

Author(s):

Eric A. Iverson ◽

David A. Goodman ◽

Madeline E. Gorchels ◽

Kenneth M. STEDMAN

Keyword(s):

Capsid Protein ◽

Major Capsid Protein ◽

Point Mutations ◽

Site Directed Mutagenesis ◽

Vp1 Gene ◽

Vp1 Protein ◽

Transposon Insertion ◽

N Terminus ◽

Capsid Protein Vp1 ◽

Virion Formation

Viruses with spindle or lemon-shaped virions are rare in the world of viruses, but are common in viruses of archaeal extremophiles, possibly due to the extreme conditions in which they thrive. However, the structural and genetic basis for the unique spindle shape is unknown. The best-studied spindle-shaped virus, SSV1, is composed mostly of the major capsid protein VP1. Similar to many other viruses, proteolytic cleavage of VP1 is thought to be critical for virion formation. Unlike half of the genes in SSV1, including the minor capsid protein VP3, the vp1 gene does not tolerate deletion or transposon insertion. In order determine the role of the vp1 gene and its proteolysis for virus function, we developed techniques for site-directed mutagenesis of the SSV1 genome and complemented deletion mutants with vp1 genes from other SSVs. By analyzing these mutants we demonstrate that the N-terminus of the VP1 protein is required, but the N-terminus, or entire SSV1 VP1 protein, can be exchanged with VP1s from other SSVs. However, the conserved glutamate at the cleavage site is not essential. Interestingly, viruses containing point mutations at this position generate mostly abnormal virions.

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Virion assembly defect of polyomavirus hr-t mutants: underphosphorylation of major capsid protein VP1 before viral DNA encapsidation.

Journal of Virology ◽

10.1128/jvi.54.2.311-316.1985 ◽

1985 ◽

Vol 54 (2) ◽

pp. 311-316 ◽

Cited By ~ 26

Author(s):

R L Garcea ◽

K Ballmer-Hofer ◽

T L Benjamin

Keyword(s):

Capsid Protein ◽

Major Capsid Protein ◽

Viral Dna ◽

Virion Assembly ◽

Capsid Protein Vp1 ◽

Assembly Defect

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Parvovirus LuIII transducing vectors packaged by LuIII versus FPV capsid proteins: the VP1 N-terminal region is not a major determinant of human cell permissiveness

Journal of General Virology ◽

10.1099/vir.0.19490-0 ◽

2004 ◽

Vol 85 (5) ◽

pp. 1251-1257 ◽

Cited By ~ 1

Author(s):

Ian H. Maxwell ◽

Françoise Maxwell

Keyword(s):

Capsid Protein ◽

Human Cell ◽

Major Capsid Protein ◽

Human Cells ◽

Terminal Region ◽

Major Determinant ◽

Capsid Proteins ◽

Entry Level ◽

Capsid Protein Vp1 ◽

Post Entry

Human cell lines are permissive for LuIII, a member of the rodent group of autonomous parvoviruses. However, LuIII vectors pseudotyped with feline panleukopaenia virus (FPV) capsid proteins can transduce feline cells but not human cells. Feline transferrin receptor (FelTfR) functions as a receptor for FPV. Transfection of Rh18A, a human rhabdomyosarcoma cell line, with FelTfR enabled transduction by vector with FPV capsid. This was not true of other human lines, suggesting restriction at some additional, post-entry, level(s) in human cells other than Rh18A. It seemed a reasonable hypothesis that a second blockage might be in nuclear delivery mediated by the N-terminal region of the minor capsid protein, VP1. We therefore generated virions containing an LuIII–luciferase genome, packaged using chimaeric VP1 molecules (N-terminal region of LuIII VP1, fused with body of FPV, and vice versa) together with the major capsid protein, VP2, of FPV or LuIII. The virions were tested for ability to transduce feline and human cells. Our hypothesis predicted that the N-terminal region of LuIII VP1 should allow transduction of human cells expressing FelTfR, while the FPV N-terminal region should not allow transduction of human cells (except for Rh18A). The experimental results did not bear out either of these predictions. Therefore, the VP1 N-terminal region appears not to be a major determinant of permissiveness for LuIII, versus FPV, capsid in human cells.

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