Helix-Turn-Helix DNA binding domain of the transcription regulators NolA and AlbR
Helix-turn-helix (HTH) transcription regulators NolA and AlbR, N-terminal domain. In Bradyrhizobium (Arachis) sp. NC92, NolA is required for efficient nodulation of host plants. In Xanthomonas albilineans, AlbR regulates the expression of the pathotoxin, albicidin. These proteins are putatively comprised of distinct domains that harbor the regulatory (effector-binding) site and the active (DNA-binding) site. Their conserved N-terminal domains contain predicted winged HTH motifs that mediate DNA binding, while the C-terminal domains are often unrelated and bind specific coactivator molecules. They 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.