To test if Ded1p can also stimulate the activity of the tombusvirus replicase on (+)-stranded RNA templates, we used DI-72(+) RNA in the purified tombusvirus replicase assay ( Figure  S4A ). The TBSV (+)RNA is known to carry a replication silencer element (RSE) at the 39 end that inhibits (2)RNA synthesis in vitro [45] . Addition of Ded1p to the tombusvirus replicase assay did not enhance (2)RNA synthesis ( Figure S4B , lane 3 versus 1-2). Also, D1 mutant deficient in ATPase activity had not much effect on (2)RNA synthesis ( Figure S4B , lane 4 versus 1-2). Based on these data, we suggest that Ded1p does not affect (2)RNA synthesis by the tombusvirus replicase in vitro.