The C-terminal end of AraC tightly binds to the rest of its domain

Genes were synthesized to express two DNA binding domains of AraC connected by short linkers. The abilities of the resulting proteins to bind to DNA containing AraC half-sites separated by the usual four bases as well as an additional two or three helical turns of the DNA were measured. The inability of some of the protein constructs to bind to widely separated half-sites indicates that the C-terminal 14 amino acids of AraC are firmly bound to the rest of the DNA binding domain.