Tex (toxin expression) is a highly conserved bacterial protein involved in expression of critical toxin genes [<cite idref="PUB00044514"/>]. The overall structure is notably flat and elongated. The most striking structural feature is a long, central helix comprising from amino acid residue 274 to 322. The rest of the protein wraps around the central helix at both the N-terminal and C-terminal ends. Although the Tex structure is fairly compact, it can be largely described as a series of distinct domains [<cite idref="PUB00050835"/>].This entry represents an N-terminal domain with a helix-turn-helix structure.