Undermethylated transfer RNA does not support phage RNA-directed in vitro protein synthesis.

A cell-free protein synthesis system from Escherichia coli Q13 was depleted of mRNA and tRNA so that restoration of maximum activity was dependent of the addition of these components. Protein synthesis, directed by either MS2 or Qbeta phage RNA, was stimulated significantly by the addition of normal tRNA from either E. coli Q13 or B. In contrast, undermethylated tRNA from methionine-starved E. coli RCrel did not cause this stimulation. It is concluded that undermethylated tRNA Lacks sufficient base modifications to function in protein synthesis.