The C protein of wild-type measles virus has the ability to shuttle between the nucleus and the cytoplasm.
Measles virus (MV) C protein is a small and basic non-structural protein, but its function is not well understood. We have found that a FLAG-tagged wild-type MV C protein expressed from cDNA was accumulated exclusively in the nucleus. To analyze the amino acid sequence important for the nuclear localization of C protein, a plasmid expressing C protein fused to the enhanced green fluorescent protein (EGFP) was generated. Mutation analysis revealed that (41)PPARKRRQ(48), belonging to the classical nuclear localization signal was important for nuclear localization. Analysis of the amino acid sequence of C protein revealed that it has a nuclear export signal (NES)-like sequence, (76)LEKAMTTLKL(85). Addition of the putative NES to the EGFP resulted in the translocation of EGFP to the cytoplasm. The Rev(1.4)-EGFP nuclear export assay showed that this putative NES has a CRM1-dependent NES activity. C-EGFP accumulated in HeLa nuclei could be translocated to NIH3T3 nuclei in heterokaryon assays. In MV-infected cells, C-EGFP was accumulated in the nuclei in early phase but in the cytoplasm in late phase. These results indicate that the putative NES is functional and that C protein has the ability to shuttle between the nucleus and the cytoplasm.
Nishie
Tomomi
T
Department of Infection Biology, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
Nagata
Kyosuke
K
Takeuchi
Kaoru
K
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008459:Measles virus / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D049790:Nuclear Export Signals / Q000235:genetics; D019913:Nuclear Localization Signals / Q000737:chemistry; D014709:Vero Cells; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D049790:Nuclear Export Signals; D019913:Nuclear Localization Signals; D017361:Viral Nonstructural Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins