TopicPage for AraC Transcriptional Activator Family of Escherichia coli K-12
| || Transcription Factors Transcriptional Regulator Families         |
The AraC Transcriptional Activator Family, also called the AraC/XylS family, is a group of related transcription factors that can activate transcription by stimulating transcription initiation (Ibara, 2008). The AraC family is within the Helix-Turn-Helix (HTH) superfamily of DNA binding proteins. AraC was the first example of a positive transcriptional regulator (Englesberg, 1965; Sheppard, 1967). AraC was also one of the first examples of DNA looping (Dunn, 1984; Martin, 1986; Schlief, 1987)
Ibarra (2008) (Supplementary Data, in "Escherichia coli K12 Tree") list 27 AraC family members in E. coli K-12 identified by Perez-Rueda (2000) . The same 27 members are also identified as hits to COG2207, with one addition (pseudogene yneL') not listed by Ibarra (2008). Two AraC family members in E. coli K-12 are pseudogenes and 26 are intact genes. Ibarra (2008) fails to recognized that ykgA' is a pseudogene. For Ada, the N-terminal domain is an AraC family regulator. Many members can also act as repressors at some promoters in the absense of co-activator. RhaSR and GadXW are adjacent genes and may have arisen by paralogous tandem gene duplication.
Additional information can be found at RegulonDB and within entries in the various motif/profile databases PFAM, InterPro, SCOP, etc.
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