Structural Insight into the Arms Race between Tomato Mosaic Virus and the Resistance Gene Tm-1

Abstract

The Tm-1 gene of tomato encodes a 754-aa protein that binds tomato mosaic virus (ToMV) replication proteins and inhibits viral RNA replication. We determined a crystal structure of complex of an N-terminal fragment of Tm-1 and helicase domain of ToMV (ToMV-Hel). The residues in ToMV-Hel that are changed in resistance-breaking mutants are directly involved in the interaction. The positively selected region of Tm-1 formed the binding surface with ToMV-Hel. Thus, the antagonistic coevolution between a resistance protein and a viral protein has occurred at the interaction interface on both sides.