| Primary Identifier | IPR004409 | Type | Domain |
| Short Name | Biotin_operon_repress_HTH |
| description | The biotin operon of Escherichia coli contains 5 structural genes involved in the synthesis of biotin. Transcription of the operon is regulated via one of these proteins, BirA. BirA is an asymetric protein with 3 specific domains. The ligase reaction intermediate, biotinyl-5'-AMP, is the co-repressor that triggers DNA binding by BirA.The α-helical N-terminal domain of the BirA protein has the helix-turn-helix structure of DNA-binding proteins with a central DNA recognition helix. BirA undergoes several conformational changes related to repressor function and the N-terminal DNA-binding function is connected to the rest of the molecule through a hinge which will allow relocation of the domains during the reaction []. Two repressor molecules form the operator-repressor complex, with dimer formation occuring simultaneously with DNA binding. DNA-binding may cause a conformational change which allows this co-operative interaction. In the dimer structure, the β-sheets in the central domain of each monomer are arranged side-by-side to form a single, seamless β-sheet. |
