The transcriptional regulator EarA and intergenic terminator sequences modulate archaellation inPyrococcus furiosus

Abstract

ABSTRACTThe regulation of archaellation, the formation of archaeal flagella-like appendages called archaella, is crucial for the motility, adhesion, and survival of archaeal organisms. Although the heavily archaellated and highly motilePyrococcus furiosusis a key model organism for understanding the production and function of archaella in Euryarchaea, the transcriptional regulation of archaellum assembly is so far unknown. Here we show that the transcription factor EarA is the master regulator of the archaellum (arl) operon transcription, which is further modulated by intergenic transcription termination signals.EarAdeletion or overexpression strains demonstrate that EarA is essential for archaellation inP. furiosusand governs the degree of archaellation. Providing a single-molecule update on the transcriptional landscape of thearloperon inP. furiosus, we identify sequence motifs for EarA binding upstream of thearloperon and intergenic terminator sequences as critical elements for fine-tuning the expression of the multicistronicarlcluster. Furthermore, transcriptome re-analysis across differentThermococcalesspecies demonstrated a heterogeneous production of major archaellins, suggesting a more diverse composition of archaella than previously recognized. Overall, our study provides novel insights into the transcriptional regulation of archaellation and highlights the essential role of EarA inPyrococcus furiosus. These findings advance our understanding of the mechanisms governing archaellation and have implications for the functional diversity of archaella.