Transcriptional regulation in halophilic archaea: Promoter elements, key transcription factor families, and gene regulatory networks

Halophilic archaea are extremophilic microorganisms adapted to thrive in highly saline environments. Their survival hinges on their capacity to respond effectively to environmental fluctuations. Microorganisms employ various strategies to regulate gene expression, with transcription factors (TFs) playing a pivotal role. These proteins govern gene expression in response to small ligands or intracellular signals. Although transcription regulation has been extensively investigated in Bacteria and Eukarya, understanding this process in haloarchaea (Archaea domain) remains limited. This work compiles and reviews the comprehensive array of transcriptional regulators that govern gene regulation in haloarchaea. The principal proteins and DNA elements involved in transcriptional initiation and regulation in haloarchaea, as well as the gene regulatory networks (GRNs) have been included. In addition, bacterial and archaeal transcriptional factors differences regarding family abundance, size, isoelectric point, and functional roles have been analyzed. Furthermore, the determinants of halophilic DNA-protein interactions are also reviewed. This analysis sheds light on haloarchaeal gene regulation and provide a strong base for further exploration and characterization of molecular machinery of these genuine microorganisms.