Autorepression

Autorepression is a regulatory mechanism in which a gene product inhibits its own expression. In transcriptional autorepression, a protein, typically a transcriptional repressor, binds to a regulatory element near the gene it encodes—such as its promoter or an operator site—reducing transcription of that gene. This creates a negative feedback loop that helps stabilize the level of the protein within the cell.

Mechanistically, the repressor’s DNA-binding activity can be modulated by small molecules, environmental signals, or other proteins, allowing the cell to tune autoregulation in response to conditions. Binding to the gene’s own regulatory region results in decreased production of the repressor, while changes in conditions can relieve repression and permit resumed transcription.

Autorepression occurs across domains of life. In bacteria, negative autoregulation is a common feature among transcriptional repressors and is often part of larger stress or growth-regulation networks; for example, certain repressors involved in the SOS response autorepress their own genes. In eukaryotes, autorepression can be more complex due to chromatin structure and multi-element regulatory architectures, but the core principle of self-induced negative feedback remains.

Functional consequences include reduced expression noise, faster return to baseline after perturbations, and tighter control of protein abundance. Negative autoregulation can speed up system responses and prevent overshoot, contributing to the stability of gene regulatory networks. It is frequently employed in synthetic biology to construct robust, tunable circuits, sometimes in combination with other regulatory motifs. Autorepression is contrasted with positive autoregulation, in which the gene product promotes its own expression.