The caiTABCDE operon is activated under anaerobic conditions to facilitate the anaerobic metabolism of carnitine. The operon is primarily activated by the ArcA protein, which is phosphorylated by ArcB in response to a reduced quinone pool under low oxygen conditions. This phosphorylated ArcA (ArcA-P) binds upstream of the operon, initiating transcription. Additionally, the CaiF transcriptional activator is induced by the cAMP-CRP complex, which forms when intracellular cAMP levels rise in response to low glucose availability, further enhancing transcription of the operon. The operon encodes proteins like CaiT, a membrane antiporter for L-carnitine, CaiA, CaiB, CaiC, and CaiD, which catalyze various reactions necessary for carnitine metabolism, ensuring efficient energy production under anaerobic conditions.

Operon: Carnitine Operon References