Formation of phenylalanine transfer RNA lacking the wye base in Vero cells during methionine starvation.

Vero, a cell line derived from African green monkey kidney, normally contains a single species of tRNAPhe (tRNA2Phe), containing a hypermodified base, wye (originally called Y), next to the 3' end of the anticodon. When methionine is removed from the growth medium, there appears a new tRNAPhe species (tRNA1Phe) lacking the wye base and eluting early from reversed phase chromatography columns. Its appearance is not due to the cessation of cell growth. Addition of methionine to cells containing both species of tRNAPhe leads to the disappearance of tRNA1Phe. When [methyl-3H5methionine is added in the presence of actinomycin D, which blocks new RNA synthesis, label appears in the wye base of tRNA2Phe. These results are consistent with the model that tRNA1Phe is an undermodifed precursor of tRNA2Phe and that methionine is required for modification to the mature form.