Nuclear import of Maize chlorotic mottle virus capsid protein is mediated by importin-α
2016
Zhan, Binhui | Lang, Fei | Zhou, Tao | Fan, Zaifeng
Maize chlorotic mottle virus (MCMV), one of the important pathogens causing corn lethal necrosis disease, possesses a positive-sense single-stranded RNA genome. Subcellular localization of MCMV coat protein (CP) was investigated by tagging with fluorescent proteins to explore its role in virus infection. Our results showed that the CP fusion proteins can be imported into the nucleus, and the N-terminal region rich in basic amino acids is essential for its nuclear localization. Bimolecular fluorescence complementation assays in maize protoplasts demonstrated that the MCMV CP interacted with the nuclear import factor importin-α1a (ZmIMPα1a) and importin-α1b (ZmIMPα1b), which suggests that the nuclear import of MCMV CP is mediated by the classical importin-α/β pathway in plants. We also found that both ZmIMPα1a and ZmIMPα1b expression were up-regulated in maize tissues at 7 d and 10 d post MCMV inoculation, respectively. Silencing ZmIMPα1a and ZmIMPα1b expression simultaneously using the Brome mosaic virus-based silencing vector decreased MCMV accumulation significantly. Our results demonstrated the nuclear import of MCMV CP and imply a role of ZmIMPα1a and ZmIMPα1b during MCMV infection.
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