title: The NS2 proteins of parvovirus minute virus of mice are required for efficient nuclear egress of progeny virions in mouse cells.
abstract: The small nonstructural NS2 proteins of parvovirus minute virus of mice (MVMp) were previously shown to interact with the nuclear export receptor Crm1. We report here the analysis of two MVM mutant genomic clones generating NS2 proteins that are unable to interact with Crm1 as a result of amino acid substitutions within their nuclear export signal (NES) sequences. Upon transfection of human and mouse cells, the MVM-NES21 and MVM-NES22 mutant genomic clones were proficient in synthesis of the four virus-encoded proteins. While the MVM-NES22 clone was further able to produce infectious mutant virions, no virus could be recovered from cells transfected with the MVM-NES21 clone. Whereas the defect of MVM-NES21 appeared to be complex, the phenotype of MVM-NES22 could be traced back to a novel distinct NS2 function. Infection of mouse cells with the MVM-NES22 mutant led to stronger nuclear retention not only of the NS2 proteins but also of infectious progeny MVM particles. This nuclear sequestration correlated with a severe delay in the release of mutant virions in the medium and with prolonged survival of the infected cell populations compared with wild-type virus-treated cultures. This defect could explain, at least in part, the small size of the plaques generated by the MVM-NES22 mutant when assayed on mouse indicator cells. Altogether, our data indicate that the interaction of MVMp NS2 proteins with the nuclear export receptor Crm1 plays a critical role at a late stage of the parvovirus life cycle involved in release of progeny viruses.
authors.affiliation: Department of Applied Tumor Virology, INSERM U375-Abteilung F0100, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 242, D-69120 Heidelberg, Germany.
authors.forename: Virginie
authors.initials: V
authors.lastname: Eichwald
authors.forename: Laurent
authors.initials: L
authors.lastname: Daeffler
authors.forename: Michèle
authors.initials: M
authors.lastname: Klein
authors.forename: Jean
authors.initials: J
authors.lastname: Rommelaere
authors.forename: Nathalie
authors.initials: N
authors.lastname: Salomé
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D028884:Karyopherins / Q000378:metabolism*; D051379:Mice; D008915:Minute Virus of Mice / Q000235:genetics / Q000378:metabolism*; D016296:Mutagenesis; D018160:Receptors, Cytoplasmic and Nuclear; D014162:Transfection; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism*; D014771:Virion; D000097606:Exportin 1 Protein
chemical_list: D028884:Karyopherins; D018160:Receptors, Cytoplasmic and Nuclear; D017361:Viral Nonstructural Proteins; D000097606:Exportin 1 Protein