Single Amino Acid Substitution in the Tobacco Mosaic Virus ORF6 Protein Suppresses Formation of Complex with eEF1A and Cooperative Nucleic Acids Binding in vitro

摘要

The translation elongation factor eEF1A plays a major role in the life cycle of the tobacco mosaic virus (TMV). It is known that eEF1A interacts with the tRNA-like structure and two pseudoknots in the 3'-untranslated region (3'-UTR) of TMV RNA as well as interacts with the methyltransferase domain of the RNA-dependent RNA polymerase and the ORF6 protein. In this work, we studied the interaction of eEF1A with the ORF6 protein of TMV strain L (ORF6-L) and with a set of mutants ORF6-L and ORF6 of TMVstrain K (ORF6-K) in vitro. It is shown that the substitution of the isoleucine residue with the threonine residue at position 11 of ORF6-L and ORF6-K (I1 1T substitution) blocks the formation of a complex with eEF1 A. It was found that the ORF6 protein is able to cooperatively bind nucleic acids and that the I1 1T substitution not only affects the interaction with eEF1A but also abolishes the cooperative binding of nucleic acids to the ORF6 protein.