Host factors with regulatory roles in tombusvirus replication

Similar to animal viruses, the abundant plant positive-strand RNA viruses replicate in infected cells by exploiting the vast resources of the host. This review focuses on virus–host interactions during tombusvirus replication. The multifunctional tombusvirus p33 replication protein not only interacts with itself, the viral p92pol polymerase, and viral RNA, but also with approximately 100 cellular proteins and subcellular membranes. Several negative regulatory host proteins, such as cyclophilins and WW motif containing proteins, also bind to p33 and interfere with p33's functions. To explain how p33 can perform multiple functions, we propose that a variety of interactions involving p33 result in the commitment of p33 molecules to specific tasks. This facilitates tight spatial and temporal organization of viral replication in infected cells.

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► The p33 replication protein of tombusviruses binds to other p33 molecules, the viral p92pol and the viral RNA.
► p33 also interacts with ∼100 cellular proteins and subcellular membranes.
► Mechanism of stimulation of TBSV replication by several host factors.
► The role of several host factors in inhibition of TBSV replication.
► We propose a ‘commitment’ model to explain the multifunctionality of p33 during viral infections.