Abstract
Relative RNA abundance was measured at different cell-cycle stages in synchronized cultures of the hyperthermophilic archaeon Sulfolobus acidocaldarius. Cyclic induction was observed for >160 genes, demonstrating central roles for transcriptional regulation and cell-cycle-specific gene expression in archaeal cell-cycle progression. Many replication genes were induced in a cell-cycle-specific manner, and novel replisome components are likely to be among the genes of unknown function with similar induction patterns. Candidate genes for the unknown genome segregation and cell division machineries were also identified, as well as seven transcription factors likely to be involved in cell-cycle control. Two serine-threonine protein kinases showed distinct cell-cycle-specific induction, suggesting regulation of the archaeal cell cycle also through protein modification. Two candidate recognition elements, CCR boxes, for transcription factors in control of cell-cycle regulons were identified among gene sets with similar induction kinetics. The results allow detailed characterization of the genome segregation, division, and replication processes and may, because of the extensive homologies between the archaeal and eukaryotic information machineries, also be applicable to core features of the eukaryotic cell cycle.