Attenuation (in genetics) is a proposed mechanism of control in some bacterial
operons which results in premature termination of
transcription and which is based on the fact that, in bacteria, transcription and
translation proceed simultaneously. Attenuation involves a provisional stop signal (attenuator), located in the DNA segment that corresponds to the leader sequence of mRNA. During attenuation, the ribosome becomes stalled (delayed) in the attenuator region in the mRNA leader. Depending on the metabolic conditions, the attenuator either stops transcription at that point or allows read-through to the structural gene part of the mRNA and synthesis of the appropriate protein.