Ligand-binding domain of MalI, a transcription regulator of the maltose system of Escherichia coli and its close homologs from other bacteria
This group includes the ligand-binding domain of MalI, a transcription regulator of the maltose system of Escherichia coli and its close homologs from other bacteria. They are members of the LacI-GalR family of repressor proteins which are composed of two functional domains: an N-terminal HTH (helix-turn-helix) domain, which is responsible for the DNA-binding specificity, and a C-terminal ligand-binding domain, which is homologous to the sugar-binding domain of ABC-type transport systems that contain the type I periplasmic binding protein-like fold. As also observed in the periplasmic binding proteins, the C-terminal domain of the bacterial transcription repressor undergoes a conformational change upon ligand binding which in turn changes the DNA binding affinity of the repressor.
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