S-adenosyl-L-methionine-dependent protein-lysine N-methyltransferase that trimethylates elongation factor 1-alpha (TEF1 and TEF2) at 'Lys-79' (PubMed:25446118). Required for replication of Brome mosaic virus (BMV) (PubMed:14671320). Present with 3060 molecules/cell in log phase SD medium. Belongs to the class I-like SAM-binding methyltransferase superfamily. EFM5 family. Was originally thought to be an N(6)-adenine-specific DNA methyltransferase based on primary sequence and predicted secondary structure.