The three-dimensional structure of trp repressor

The crystal structure of the Escherichia coli trp repressor has been solved to atomic resolution. The dimeric protein has a remarkable subunit interface in which five of each subunit's six helices are interlinked. The binding of L-tryptophan activates the aporepressor indirectly by fixing the orientation of the second helix of the helix-turn-helix motif and by moulding the details of the repressor's structure near the DNA binding surface.