Negatively regulates glucose metabolism by binding directly to the promoter region of the kgu and gad operons (PubMed:20581202). It also negatively regulates its own synthesis (PubMed:20581202). 2-ketogluconate acts as a molecular effector and causes dissociation of PtxS from its target promoter. Homodimer in solution. Negatively autoregulates its own synthesis by binding to a specific operator site within the ptxS upstream region. Contains an N-terminal helix-turn-helix DNA-binding domain and a C-terminal domain that binds the effector.