Helix-Turn-Helix DNA binding domain of the transcription regulators TipAL, Mta, and SkgA
Helix-turn-helix (HTH) TipAL, Mta, and SkgA transcription regulators, and related proteins, N-terminal domain. TipAL regulates resistance to and activation by numerous cyclic thiopeptide antibiotics, such as thiostrepton. Mta is a global transcriptional regulator; the N-terminal DNA-binding domain of Mta interacts directly with the promoters of mta, bmr, blt, and ydfK, and induces transcription of these multidrug-efflux transport genes. SkgA has been shown to control stationary-phase expression of catalase-peroxidase in Caulobacter crescentus. These proteins are comprised of distinct domains that harbor an N-terminal active (DNA-binding) site and a regulatory (effector-binding) site. The conserved N-terminal domain of these transcription regulators contains winged HTH motifs that mediate DNA binding. These proteins share the N-terminal DNA binding domain with other transcription regulators of the MerR superfamily that promote transcription by reconfiguring the spacer between the -35 and -10 promoter elements. Unique to this family, is a TipAL-like, lineage specific Bacilli subgroup, which has five conserved cysteines in the C-terminus of the protein.