L-arabinose operon

[2] AraB (ribulokinase), AraA (an isomerase), and AraD (an epimerase) produced by these genes catalyse conversion of L-arabinose to an intermediate of the pentose phosphate pathway, D-xylulose-5-phosphate.

[2] The structural genes of the L-arabinose operon are transcribed from a common promoter into a single transcript, a mRNA.

[3] The expression of the L-arabinose operon is controlled as a single unit by the product of regulatory gene araC and the catabolite activator protein (CAP)-cAMP complex.

[7] The structural genes, araB, araA and araD, encode enzymes for L-arabinose catabolism.

Both araC and araBAD have a discrete promoter where RNA polymerase binds and initiates transcription.

[6] The L-arabinose system is not only under the control of CAP-cAMP activator, but also positively or negatively regulated through binding of AraC protein.

AraC functions as a homodimer, which can control transcription of araBAD through interaction with the operator and the initiator region on L-arabinose operon.

Hence, it is more energetically favourable for AraC-arabinose to bind to two adjacent DNA half sites: araI1 and araI2 in the presence of arabinose.

[16] The L-arabinose operon has been a focus for research in molecular biology since 1970, and has been investigated extensively at its genetic, biochemical, physiological and biotechnical levels.