| Definition: |
Translational attenuation is a regulatory mechanism analogous to ribosome-mediated transcriptional attenuation. The system requires the presence of a short ORF, called a leader peptide, encoded in the mRNA upstream of the ribosome-binding site and start codon of the gene whose translation is to be regulated. Certain conditions, such as presence of the antibiotic tetracycline in bacteria or amino acid starvation, may cause slowing or stalling of the ribosome translating the leader peptide. The stalled ribosome masks a region of the mRNA and affects which of two alternative mRNA folded structures will form, therefore controlling whether or not a ribosome will bind and initiate translation of the downstream gene. Translational attenuation is analogous to ribosome-mediated transcriptional attenuation, in which mRNA remodeling caused by ribosome stalling regulates transcriptional termination rather than translational initiation. |