Nuclear localization of non-structural protein 1 and nucleocapsid protein of equine arteritis virus.
RNA synthesis (genome replication and subgenomic mRNA transcription) directed by equine arteritis virus (EAV; family Arteriviridae, order Nidovirales) occurs on modified cytoplasmic membranes to which most viral replicase subunits localize. Remarkably, a fraction of non-structural protein 1 (nsp1), a protein essential for transcription but dispensable for genome replication, is present in the host cell nucleus, in particular during the earlier stages of infection. Expression of GFP-tagged fusion proteins revealed that nsp1 is actively imported into the nucleus. Although the signals responsible for nsp1 transport could not be identified, our studies revealed that another EAV protein with a partially nuclear localization, the nucleocapsid (N) protein, utilizes the CRM1-mediated nuclear export pathway. Inactivation of this pathway with the drug leptomycin B resulted in the unexpected and immediate nuclear retention of all N protein molecules, thus revealing that the protein shuttles between cytoplasm and nucleus before playing its role in cytoplasmic virus assembly.
Tijms
Marieke A
MA
Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, LUMC E4-P, PO Box 9600, 2300 RC Leiden, The Netherlands1.
van der Meer
Yvonne
Y
Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, LUMC E4-P, PO Box 9600, 2300 RC Leiden, The Netherlands1.
Snijder
Eric J
EJ
Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, LUMC E4-P, PO Box 9600, 2300 RC Leiden, The Netherlands1.
D021581:Active Transport, Cell Nucleus; D002467:Cell Nucleus / Q000378:metabolism*; D007240:Equartevirus / Q000378:metabolism*; D008970:Molecular Weight; D019251:Nucleocapsid / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D019065:Virus Assembly
D017361:Viral Nonstructural Proteins