The high frequency of lyzogenization (hfl) operon is a polycistronic operon consisting of the genes: hfq, hflX, hflK and hflC. hfq encodes the RNA-binding protein Hfq which aids in RNA stability , hflX encodes a GTPase involved in ribosomal assembly, hflK encodes a membrane-associated protein and hflC encodes a protease regulatory subunit which regulates protease activity, affecting lysogeny and other cellular processes. This operon is regulated by CRP-cAMP DNA-binding transcriptional dual regulator being binded to a crp binding site in the -96.5 bp from the promoter, thus activating the transcription of the hfl operon. This activation is dependent on the presence of cAMP, which is high when glucose levels are low. The pathway is repressed when cAMP levels decrease when glucose levels are high, thus preventing formation of CRP-cAMP complex. This in turn prevents RNA polymerase from binding efficiently to the promoter thus repressing transcription

Operon: High Frequency of Lysogenization Repression References