Host membrane proteins involved in the replication of tobamovirus RNA

Eukaryotic positive-strand RNA viruses replicate their genomes in membrane-bound replication complexes composed of viral replication proteins and negative-strand RNA templates. These replication proteins are programmed to exhibit RNA polymerase and other replication-related activities only in replication complexes to avoid inducing double-stranded RNA-mediated host defenses. Host membrane components (e.g. proteins and lipids) should play important roles in the activation of replication proteins. Two host membrane proteins are components of the replication complex and activate the replication proteins of tobamoviruses. Interaction analyses using deletion mutants constructed based on structural information suggest a conformational change in replication proteins during the formation of a protein complex with RNA 5′-capping activity.

► Host membrane proteins TOM1 and ARL8 are essential for tobamovirus RNA replication. ► They constitute tobamovirus replication complex with viral replication proteins. ► The replication protein gains RNA 5′ capping activity when bound to TOM1 and ARL8. ► Such programmed activation of replication functions may help to avoid host defense.