Question

In bacteria, the process of translation affects the speed of transcription—efficient binding and progression of ribosomes along the mRNA increases the speed of transcription, whereas the absence of ribosomes on the mRNA slows the movement of RNA polymerase along the DNA. Treatment of bacteria with an antibiotic that inhibits translation slows the progression of RNA polymerase along the DNA. Likewise, if ribosomal proteins are mutated in a way that slows or inhibits translation, the process of transcription also slows. Furthermore, mutations in ribosomes that speed up the process of translation also accelerate transcription.

Propose a mechanism for how the process of translation could affect the speed of transcription.

Answer 1

Attenuation or dampening, of the trp operon is made possible by the fact that the rate of translation influences RNA structure, which in turn influences the rate of transcription.Translation therefore interferes with transcription, making this an example of translation-mediated transcription attenuation Mechanistically, this kind of attenuation is achieved because special sequences located near the beginning of the transcript, called the leader (trpL), interact to create two possible RNA conformations: one that terminates transcription (the terminator stem), and one that is permissive to transcription (the anti-terminator stem)

The mechanism by which formation of the terminator stem disrupts continued transcription is now understood. Recent studies have revealed that the formation of this kind of secondary structure in RNA upstream of RNA polymerase can lead to dissolution of the RNA polymerase/DNA complex and thus a shut-down of further transcription.