Strain-specific interaction of the tobacco etch virus Nla protein with the translation initiation factor elF4E in the yeast two-hybrid system

The Nla protein of potyviruses provides VPg and proteolytic functions during virus replication. It has also been shown to confer host genotype-specific movement functions in plants. Specifically, Nla from tobacco etch virus (TEV)-Oxnard, but not from most other strains, confers the ability to move long distances in Nicotiana tabacum cultivar 'V-20.' This led to the hypothesis that all or part of Nla may interact with one or more cellular factors. To identify cellular proteins that interact with Nla in a host- or strain-specific manner, a yeast two-hybrid search of a tomato cDNA library was done. Ten proteins that interacted with Nla were recovered, with translation initiation factor elF4E being by far the most common protein identified. Interaction of elF4E with Nla was shown to be TEV strain-specific. elF4E from both tomato and tobacco interacted well with Nla from the HAT strain, but not from the Oxnard strain. However, using chimeric Nla proteins, the determinant for systemic infection of V20 plants was found to be genetically distinct from the determinant controlling elF4E interaction. In TEV-elF4E coexpression experiments, evidence suggesting that elF4E provides a positive effect on genome amplification was obtained. (C) 2000 Academic Press.