Expression of promoters with no UP element. Expression of promoters with no UP element. Model predictions using (A) an energy matrix (Eq. 1) where the −35 and −10 elements independently contribute to RNAP binding and (B) a multivalent model (Eq. 3) where the two sites contribute cooperatively. (A, Inset) The epistasis-free nature of the energy matrix model makes sharp predictions about the gene expression of the consensus −35 and −10 sequences that markedly disagree with the data. Parameter values are given in SI Appendix, section B. Tal Einav, and Rob Phillips PNAS doi:10.1073/pnas.1905615116 ©2019 by National Academy of Sciences