title: VP1, the major capsid protein of the mouse polyomavirus, binds microtubules, promotes their acetylation and blocks the host cell cycle.
abstract: VP1, the major structural protein of the mouse polyomavirus (MPyV), is the major architectural component of the viral capsid. Its pentamers are able to self-assemble into capsid-like particles and to non-specifically bind DNA. Surface loops of the protein interact with sialic acid of ganglioside receptors. Although the replication cycle of the virus, including virion morphogenesis, proceeds in the cell nucleus, a substantial fraction of the protein is detected in the cytoplasm of late-phase MPyV-infected cells. In this work, we detected VP1 mainly in the cytoplasm of mammalian cells transfected with plasmid expressing VP1. In the cytoplasm, VP1-bound microtubules, including the mitotic spindle, and the interaction of VP1 with microtubules resulted in cell cycle block at the G2/M phase. Furthermore, in the late phase of MPyV infection and in cells expressing VP1, microtubules were found to be hyperacetylated. We then sought to understand how VP1 interacts with microtubules. Dynein is not responsible for the VP1-microtubule association, as neither overexpression of p53/dynamitin nor treatment with ciliobrevin-D (an inhibitor of dynein activity) prevented binding of VP1 to microtubules. A pull-down assay for VP1-interacting proteins identified the heat shock protein 90 (Hsp90) chaperone, and Hsp90 was also detected in the VP1-microtubule complexes. Although Hsp90 is known to be associated with acetylated microtubules, it does not mediate the interaction between VP1 and microtubules. Our study provides insight into the role of the major structural protein in MPyV replication, indicating that VP1 is a multifunctional protein that participates in the regulation of cell cycle progression in MPyV-infected cells.
authors.affiliation: Department of Genetics and Microbiology, Faculty of Science, Charles University, Prague, Czech Republic.
authors.forename: Lenka
authors.initials: L
authors.lastname: Horníková
authors.affiliation: Department of Genetics and Microbiology, Faculty of Science, Charles University, Prague, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Fraiberk
authors.affiliation: Laboratory of Structural Biology and Cell Signaling, Institute of Microbiology, Academy of Science of the Czech Republic, Prague, Czech Republic.|Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Man
authors.affiliation: Department of Genetics and Microbiology, Faculty of Science, Charles University, Prague, Czech Republic.
authors.forename: Václav
authors.initials: V
authors.lastname: Janovec
authors.affiliation: Department of Genetics and Microbiology, Faculty of Science, Charles University, Prague, Czech Republic.
authors.forename: Jitka
authors.initials: J
authors.lastname: Forstová
mesh_terms: D000107:Acetylation; D000818:Animals; D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism / Q000821:virology; D003593:Cytoplasm / Q000378:metabolism / Q000821:virology; D004847:Epithelial Cells / Q000378:metabolism* / Q000821:virology; D005260:Female; D059565:G2 Phase Cell Cycle Checkpoints; D015870:Gene Expression; D057809:HEK293 Cells; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D008321:Mammary Glands, Animal / Q000378:metabolism / Q000821:virology; D051379:Mice; D008870:Microtubules / Q000378:metabolism* / Q000821:virology; D041681:NIH 3T3 Cells; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D011120:Polyomavirus / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D014162:Transfection; D014771:Virion / Q000235:genetics / Q000378:metabolism*
chemical_list: D036022:Capsid Proteins; D018841:HSP90 Heat-Shock Proteins; C062481:VP1 protein, polyomavirus
keywords: VP1; cell cycle arrest; chaperone Hsp90; microtubules; mouse polyomavirus