Hsp90 Interacts Specifically with Viral RNA and Differentially Regulates Replication Initiation of Bamboo mosaic virus and Associated Satellite RNA |
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| Authors: | Ying Wen Huang Chung Chi Hu Ming Ru Liou Ban Yang Chang Ching Hsiu Tsai Menghsiao Meng Na Sheng Lin Yau Heiu Hsu |
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| Institution: | 1. Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan.; 2. Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan.; 3. Institute of Biochemistry, National Chung Hsing University, Taichung, Taiwan.;University of Kentucky, United States of America |
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| Abstract: | Host factors play crucial roles in the replication of plus-strand RNA viruses. In this report, a heat shock protein 90 homologue of Nicotiana benthamiana, NbHsp90, was identified in association with partially purified replicase complexes from BaMV-infected tissue, and shown to specifically interact with the 3′ untranslated region (3′ UTR) of BaMV genomic RNA, but not with the 3′ UTR of BaMV-associated satellite RNA (satBaMV RNA) or that of genomic RNA of other viruses, such as Potato virus X (PVX) or Cucumber mosaic virus (CMV). Mutational analyses revealed that the interaction occurs between the middle domain of NbHsp90 and domain E of the BaMV 3′ UTR. The knockdown or inhibition of NbHsp90 suppressed BaMV infectivity, but not that of satBaMV RNA, PVX, or CMV in N. benthamiana. Time-course analysis further revealed that the inhibitory effect of 17-AAG is significant only during the immediate early stages of BaMV replication. Moreover, yeast two-hybrid and GST pull-down assays demonstrated the existence of an interaction between NbHsp90 and the BaMV RNA-dependent RNA polymerase. These results reveal a novel role for NbHsp90 in the selective enhancement of BaMV replication, most likely through direct interaction with the 3′ UTR of BaMV RNA during the initiation of BaMV RNA replication. |
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