and other genome factors can still influence the termination. Experimental studies have been conducted on Thermococcus Kodakarensis, an archaea found in the thermal springs and gas vents of Japan. For this species, a universal euryarchaeal termination factor called Eta was discovered. It is important to note that this factor is not a homolog of the bacterial termination factor Rho. When Eta acts on a specific transcript, it interacts with RNA polymerase as well as upstream DNA sequences on the template strand. For intrinsic termination in T. Kodakarensis, studies have shown other intrinsic structural features besides hairpin loops can lead to termination. These features include the upstream presence of an oligo-T nucleotide sequence (approximately 7-8 T nucleotides is sufficient) as well as specific intergenic terminator sequences with one to three upstream oligo T-tracts. During these studies, the presence of these structural features led to over 90% reduced expression of the reporter gene. The intergenic sequences were identified using the GeSTer Algorithm, which predicts and arranges the efficiency of intrinsic terminators. Further experiments showed that intergenic sequences carrying small induced mutations showed similar reduced expression to the wildtype intergenic sequences. This finding demonstrated that the reduced expression due to termination was not just due to the oligo T-tract or possible formation of a hairpin. See also Rho factor WebGeSTer Trp operon References Gene expression Molecular biology Prokaryotes