A MAR-like transcriptional regulator of the archaeaon Sulfolobus solfataricus binds to the alcohol dehydrogenase promoter

The understanding of basic processes in the third domain of life, Archaea, has been greatly deepened by the completion of several genome sequencing projects like that of S. solfataricus.The conversion of a sequence database into a functional one, favours the understanding of networks controlling fundamental cellular processes, like DNA repair systems, and regulatory networks. Transcription studies in Archaea have revealed that the archaeal basal machinery resembles its eukaryotic counterpart. Intriguingly, sequencing projects have evidenced the existence of homologues of bacterial transcriptional regulators To date, a few of them have been studied, but a model explaining their role in the regulation of specific metabolic genes still needs to be elucidated. In this context, to investigate mechanisms of transcription regulation in the hyperthermophilic archaeon S. solfataricus, we focused on the expression of a putative bacterial-like transcription factor that in Bacteria is involved in the regulation of genes for the degradation of aromatic compounds. The recombinant protein has been purified to homogeneity, and is a highly thermostable DNA binding protein. The encoding gene is transcriptionally regulated in response to aromatic compounds. Mobility shift assays and DNA footprinting showed that this protein has a specific target, that is an aromatic alcohol dehydrogenase (adh) gene. The correlation between adh gene regulation and the binding of a specific factor in its promoter sequence suggests that this specific interaction could be responsible for the switch on of the aromatic aldehyde metabolism in response to environmental changes.