RESUMO
Archaea form a third domain of life that is distinct from Bacteria and Eukarya. According to the current knowledge, the basal transcription machinery of Archaea (including the core promoter architecture, the RNA polymerase, and the basal transcription factors) closely resembles that of Eukarya in structure and function, while differing considerably from the bacterial paradigm. In the present study, the promoter region of the halophilic archaeon Haloarcula hispanica's amyH gene was isolated and characterized, and it was surprisingly revealed that the amyH gene promoter could confer promoter activity (i.e., drive transcription) in haloarchaea (Archaea) as well as in Escherichia coli (Bacteria), where the transcriptions driven are initiated at the same adenine base. Further investigation revealed that the core structure of the amyH gene promoter possesses a combination of the typical structural characteristics of archaeal promoter, which are eukaryotic-like, and those of bacterial promoter. Our results indicate that the core promoter structures of some archaeal genes may possess a combination of eukaryotic- and bacterial-like features, and moreover, suggest a possible evolutionary relationship between basal transcription signals and transcription mechanisms of Archaea and the other two domains of life.
