THE SEQUENCE, AND ITS EVOLUTIONARY IMPLICATIONS, OF A THERMOCOCCUS CELER PROTEIN ASSOCIATED WITH TRANSCRIPTION

Through random search, a gene from Thermococcus celer has been identif ied and sequenced that appears to encode a transcription-associated pr otein (110 amino acid residues). The sequence has clear homology to ap proximately the last half of an open reading frame reported previously for Sulfolobus acidocaldarius [Langer, D. & Zillig, W. (1993) Nucleic Acids Res. 21, 2251]. The protein translations of these two archaeal genes in turn are homologs of a small subunit found in eukaryotic RNA polymerase I (A12.2) and the counterpart of this from RNA polymerase I I (B12.6). Homology is also seen with the eukaryotic transcription fac tor TFIIS, but it involves only the terminal 45 amino acids of the arc haeal proteins. Evolutionary implications of these homologies are disc ussed.