Mechanism of ribosome frameshifting during translation of the genetic code

Some frameshift mutations are strongly suppressed by limitation for particular aminoacyl-tRNA species. Here, we show that ribosome frameshifting at a specific tryptophan codon during Trp-tRNA limitation accounts for suppression of a group of downstream frameshift alleles in the rIIB gene of bacteriophage T4. Genetic and physiological observations strongly suggest that ribosome frameshifting at this position depends on the binding of a noncognate (leucine) tRNA.