- The araBAD promoter is a tightly regulated and inducible promoter derived from the arabinose operon of Escherichia coli, which controls genes involved in arabinose metabolism.
- It is regulated by the AraC protein, which functions both as a repressor and an activator depending on the presence of L-arabinose.
- In the absence of arabinose, AraC binds to the operator in a configuration that blocks transcription.
- Upon addition of arabinose, AraC undergoes a conformational change that activates the promoter, allowing transcription to proceed.
- This dual control mechanism provides tight regulation and low basal expression, making the araBAD promoter particularly well-suited for expressing toxic or tightly regulated genes.
- Unlike IPTG-inducible systems such as lacUV5, the araBAD promoter offers graded induction—expression levels can be finely tuned by varying the concentration of arabinose in the medium.
- It is often used in expression systems such as pBAD vectors, which do not require specialized host strains and function with the host’s native RNA polymerase.
- Because arabinose is metabolizable by E. coli, precise timing and concentration control are essential for consistent results.
- Overall, the araBAD promoter provides researchers with a highly controllable, non-leaky system that is ideal for applications requiring sensitive gene regulation or minimal background expression.
