Tomato bushy stunt virus (TBSV), a plus-stranded [(+)] RNA plant virus, incorporates the host metabolic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) into the viral replicase complex. Here, we show that, during TBSV replication in yeast, the yeast GAPDH Tdh2p moves from the cytosol to the peroxisomal membrane surface, the site of viral RNA synthesis. In yeast cells lacking Tdh2p, decreasing the levels of its functionally redundant homolog Tdh3p inhibited TBSV replication and resulted in equivalent levels of (+) and minus-stranded [(-)] viral RNA, in contrast to the hallmark excess of (+)RNA. Tdh2p specifically bound an AU pentamer sequence in the (-)RNA, suggesting that GAPDH promotes asymmetric RNA synthesis by selectively retaining the (-)RNA template in the replicase complex. Downregulation of GAPDH in a natural plant host decreased TBSV genomic RNA accumulation. Thus, TBSV co-opts the RNA-binding function of a metabolic protein, helping convert the host cell into a viral factory.
|Number of pages||10|
|Journal||Cell Host and Microbe|
|State||Published - Mar 13 2008|
Bibliographical noteFunding Information:
We thank Dr. Saulius Serva for his preliminary experiments on the viral RNA binding by Tdh2p. We thank Dr. Dinesh-Kumar for pTRV1 and pTRV2 VIGS vectors; Dr. D. Lewandowski for the infectious TMV clone; and Drs. Mark Farman, Judit Pogany, David Smith, and Zsuzsanna Sasvari for critical reading of the manuscript and for very helpful suggestions. This work was supported by NIH-NIAID and by the Kentucky Tobacco Research and Development Center at the University of Kentucky, awarded to P.D.N.
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