Coat proteins of Rice tungro bacilliform virus and Mungbean yellow mosaic virus contain multiple nuclear-localization signals and interact with importin alpha.
Transport of the viral genome into the nucleus is an obligatory step in the replication cycle of plant pararetro- and geminiviruses. In both these virus types, the multifunctional coat protein (CP) is thought to be involved in this process. Here, a green fluorescent protein tagging approach was used to demonstrate nuclear import of the CPs of Rice tungro bacilliform virus (RTBV) and Mungbean yellow mosaic virus--Vigna (MYMV) in Nicotiana plumbaginifolia protoplasts. In both cases, at least two nuclear localization signals (NLSs) were identified and characterized. The NLSs of RTBV CP are located within both N- and C-terminal regions (residues 479KRPK/497KRK and 744KRK/758RRK), and those of MYMV CP within the N-terminal part (residues 3KR and 41KRRR). The MYMV and RTBV CP NLSs resemble classic mono- and bipartite NLSs, respectively. However, the N-terminal MYMV CP NLS and both RTBV CP NLSs show peculiarities in the number and position of basic residues. In vitro pull-down assays revealed interaction of RTBV and MYMV CPs with the nuclear import factor importin alpha, suggesting that both CPs are imported into the nucleus via an importin alpha-dependent pathway. The possibility that this pathway could serve for docking of virions to the nucleus is discussed.
Guerra-Peraza
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O
Friedrich Miescher Institute, Maulbeerstrasse 66, 4058 Basel, Switzerland.
Kirk
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D
Friedrich Miescher Institute, Maulbeerstrasse 66, 4058 Basel, Switzerland.
Seltzer
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Institut de Biologie Moléculaire des Plantes, UPR-CNRS 2357, Université Louis Pasteur, 12 rue du Général Zimmer, 67084 Strasbourg Cedex, France.
Veluthambi
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K
Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai 625021, India.
Schmit
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AC
Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai 625021, India.
Hohn
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University of Basel, Botanical Institute, Plant Health Unit, Schoenbeinstrasse 6, 4056 Basel, Switzerland.|Friedrich Miescher Institute, Maulbeerstrasse 66, 4058 Basel, Switzerland.
Herzog
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E
Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai 625021, India.|Friedrich Miescher Institute, Maulbeerstrasse 66, 4058 Basel, Switzerland.
D036022:Capsid Proteins / Q000378:metabolism*; D017796:Caulimovirus / Q000378:metabolism / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism*; D017791:Geminiviridae / Q000378:metabolism / Q000502:physiology*; D028884:Karyopherins / Q000378:metabolism*; D011485:Protein Binding; D014026:Nicotiana / Q000378:metabolism*; D014779:Virus Replication
D036022:Capsid Proteins; D028884:Karyopherins