Interaction of turnip yellow mosaic virus Val‐RNA with eukaryotic elongation factor EF‐1 [alpha]. Search for a function.

The 3′‐terminal tRNA‐like structure in turnip yellow mosaic virus (TYMV) RNA can be adenylated by tRNA nucleotidyltransferase and subsequently aminoacylated by valyl‐tRNA synthetase.Here we present evidence that TYMV Val‐RNA can form a stable complex with eukaryotic wheat germ elongation factor EF‐1alpha and GTP: the Val‐RNA is protected by EF‐1alpha.. GTP against digestion by RNase A. By affinity chromatography of TYMV Val‐RNA fragments on immobilized EF‐1alpha . GTP, it has been established that the valylated aminoacyl RNA domain, which in TYMV RNA is formed by the 3′ half of the tRNA‐like region, is sufficient for complex formation with EF‐1alpha . GTP. The aminoacyl RNA domain is equivalent in tRNAs to the continuous helix formed by the acceptor stem and the T stem and loop. In line with these results, the aminoacyl RNA domain in TYMV Val‐RNA complexed to EF‐1 alpha . GTP is resistant to digestion by RNase A. It is also shown that the TYMV RNA replicase (RNA‐dependent RNA polymerase) isolated from TYMV‐infected Chinese cabbage leaves does not contain tRNA nucleotidyltransferase, valyl‐tRNA synthetase or EF‐1alpha. This suggests that interaction of TYMV RNA with EF‐1alpha is not mandatory for replicase activity.