Analysis of transcription in the archaebacterium Sulfolobus indicates that archaebacterial promoters are homologous to eukaryotic pol II promoters.

The 5'-termini were precisely mapped for five constitutive and one UV-inducible transcript from the Sulfolobus virus-like particle SSV1. The comparison of the DNA sequences around these transcriptional initiation sites revealed the presence of two conserved sequence elements: a trinucleotide sequence close to the initiation site itself and an AT-rich hexanucleotide sequence centered about 26 nucleotides upstream of it. Similar DNA sequences were found upstream of the transcriptional start sites for the ribosomal RNA genes in Sulfolobus and upstream of transcriptional start sites in other archaebacteria, allowing the derivation of a general consensus sequence for archaebacterial promoters. This consensus sequence is unlike that found in eubacteria but it resembles promoters recognized by eukaryotic RNA polymerase II.